Bump countries from 5.7.2 to 6.0.0

Bumps [countries](https://github.com/countries/countries) from 5.7.2 to 6.0.0.
- [Release notes](https://github.com/countries/countries/releases)
- [Changelog](https://github.com/countries/countries/blob/master/CHANGELOG.md)
- [Upgrade guide](https://github.com/countries/countries/blob/master/UPGRADE.md)
- [Commits](countries/countries@v5.7.2...v6.0.0)

---
updated-dependencies:
- dependency-name: countries
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -9,7 +9,7 @@ GEM
   specs:
     ast (2.4.2)
     concurrent-ruby (1.2.3)
-    countries (5.7.2)
+    countries (6.0.0)
       unaccent (~> 0.3)
     i18n (1.14.4)
       concurrent-ruby (~> 1.0)