fails to build on 24.08 platform

[cbm755]

cc1plus: note: unrecognized command-line option ‘-Wno-c++98-compat’ may have been intended to silence earlier diagnostics
[4/6] Building CXX object src/CMakeFiles/discord-rpc.dir/rpc_connection.cpp.o
FAILED: src/CMakeFiles/discord-rpc.dir/rpc_connection.cpp.o 
/usr/bin/c++ -DDISCORD_BUILDING_SDK -DDISCORD_DYNAMIC_LIB -DDISCORD_LINUX -Ddiscord_rpc_EXPORTS -I/run/build/discord-rpc/include -I/app/include/rapidjson/include -O2 -pipe -g -Wp,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -fasynchronous-unwind-tables -fstack-clash-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -std=gnu++14 -fPIC -g -Wall -Wextra -Wpedantic -Wno-unknown-pragmas -Wno-old-style-cast -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-missing-noreturn -Wno-padded -Wno-covered-switch-default -Wno-exit-time-destructors -Wno-global-constructors -fPIC -MD -MT src/CMakeFiles/discord-rpc.dir/rpc_connection.cpp.o -MF src/CMakeFiles/discord-rpc.dir/rpc_connection.cpp.o.d -o src/CMakeFiles/discord-rpc.dir/rpc_connection.cpp.o -c /run/build/discord-rpc/src/rpc_connection.cpp
In file included from /run/build/discord-rpc/src/serialization.h:15,
                 from /run/build/discord-rpc/src/rpc_connection.h:4,
                 from /run/build/discord-rpc/src/rpc_connection.cpp:1:
/app/include/rapidjson/document.h: In member function ‘rapidjson::GenericStringRef<CharType>& rapidjson::GenericStringRef<CharType>::operator=(const rapidjson::GenericStringRef<CharType>&)’:
/app/include/rapidjson/document.h:319:82: error: assignment of read-only member ‘rapidjson::GenericStringRef<CharType>::length’
  319 |     GenericStringRef& operator=(const GenericStringRef& rhs) { s = rhs.s; length = rhs.length; }
      |                                                                           ~~~~~~~^~~~~~~~~~~~
At global scope:
cc1plus: note: unrecognized command-line option ‘-Wno-global-constructors’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-exit-time-destructors’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-covered-switch-default’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-c++98-compat-pedantic’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-c++98-compat’ may have been intended to silence earlier diagnostics
[5/6] Building CXX object src/CMakeFiles/discord-rpc.dir/discord_rpc.cpp.o
FAILED: src/CMakeFiles/discord-rpc.dir/discord_rpc.cpp.o 
/usr/bin/c++ -DDISCORD_BUILDING_SDK -DDISCORD_DYNAMIC_LIB -DDISCORD_LINUX -Ddiscord_rpc_EXPORTS -I/run/build/discord-rpc/include -I/app/include/rapidjson/include -O2 -pipe -g -Wp,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -fasynchronous-unwind-tables -fstack-clash-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -std=gnu++14 -fPIC -g -Wall -Wextra -Wpedantic -Wno-unknown-pragmas -Wno-old-style-cast -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-missing-noreturn -Wno-padded -Wno-covered-switch-default -Wno-exit-time-destructors -Wno-global-constructors -fPIC -MD -MT src/CMakeFiles/discord-rpc.dir/discord_rpc.cpp.o -MF src/CMakeFiles/discord-rpc.dir/discord_rpc.cpp.o.d -o src/CMakeFiles/discord-rpc.dir/discord_rpc.cpp.o -c /run/build/discord-rpc/src/discord_rpc.cpp
In file included from /run/build/discord-rpc/src/serialization.h:15,
                 from /run/build/discord-rpc/src/rpc_connection.h:4,
                 from /run/build/discord-rpc/src/discord_rpc.cpp:6:
/app/include/rapidjson/document.h: In member function ‘rapidjson::GenericStringRef<CharType>& rapidjson::GenericStringRef<CharType>::operator=(const rapidjson::GenericStringRef<CharType>&)’:
/app/include/rapidjson/document.h:319:82: error: assignment of read-only member ‘rapidjson::GenericStringRef<CharType>::length’
  319 |     GenericStringRef& operator=(const GenericStringRef& rhs) { s = rhs.s; length = rhs.length; }
      |                                                                           ~~~~~~~^~~~~~~~~~~~
At global scope:
cc1plus: note: unrecognized command-line option ‘-Wno-global-constructors’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-exit-time-destructors’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-covered-switch-default’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-c++98-compat-pedantic’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-c++98-compat’ may have been intended to silence earlier diagnostics
ninja: build stopped: subcommand failed.
FB: host_command_exited_cb 2024382 256
�]2;flatpak-builder: Cleanup discord-rpc�Error: module discord-rpc: Child process exited with code 1
FB: Unmounting read-only fs: fusermount -uz /srv/buildbot/worker/build-aarch64-7/build/.flatpak-builder/rofiles/rofiles-8apfWU
program finished with exit code 1
elapsedTime=332.061860

See Issue #58 and PR #59