Update yarn to latest stable version

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
           LAST_TEAMCITY_BUILD=650
           echo "BUILD_NUMBER=$(( $GITHUB_RUN_NUMBER + $LAST_TEAMCITY_BUILD ))" >> $GITHUB_ENV
 
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       # Setup AWS credentials to enable uploading to S3 for Riff-Raff.
       # See https://github.com/aws-actions/configure-aws-credentials
@@ -31,16 +31,18 @@ jobs:
           role-to-assume: ${{ secrets.GU_RIFF_RAFF_ROLE_ARN }}
           aws-region: eu-west-1
 
+      - run: corepack enable
+
       - name: Setup Node
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v4
         with:
           node-version-file: ".nvmrc"
 
       - name: install dependencies
         run: yarn install
 
       - name: check for duplicate dependencies (if it fails here, then pre-commit hook is not working)
-        run: yarn yarn-deduplicate --fail
+        run: yarn dedupe --check
 
       - name: generate TS definitions for GraphQL schema
         run: yarn graphql-refresh

.gitignore

@@ -13,3 +13,12 @@ cdk.out/
 
 shared/graphql/graphql.ts
 .DS_Store
+
+# See https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions

.husky/pre-commit

@@ -3,6 +3,7 @@
 
 set -e
 
+corepack enable
 yarn lint-staged
 
 if (git diff --name-only --cached | grep -e 'cdk' -e 'shared/graphql'); then
@@ -11,7 +12,7 @@ if (git diff --name-only --cached | grep -e 'cdk' -e 'shared/graphql'); then
 fi
 
 if (git diff --name-only --cached | grep 'yarn.lock'); then
-    yarn yarn-deduplicate
+    yarn dedupe
     git add yarn.lock
     yarn workspace client analyze-main-client-bundle
 fi

.nvmrc

@@ -1 +1 @@
-18.15.0
+18.20.2