Build(deps): Bump actions/cache from 2 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v2...v4)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ember_with_plugins.yml

@@ -26,7 +26,7 @@ jobs:
         run: echo "::set-output name=dir::$(yarn cache dir)"
 
       - name: Yarn cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         id: yarn-cache
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}

.github/workflows/linting.yml

@@ -28,7 +28,7 @@ jobs:
           git config --global user.name "Discourse CI"
 
       - name: Bundler cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: vendor/bundle
           key: ${{ runner.os }}-gem-${{ hashFiles('**/Gemfile.lock') }}
@@ -49,7 +49,7 @@ jobs:
         run: echo "::set-output name=dir::$(yarn cache dir)"
 
       - name: Yarn cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         id: yarn-cache
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}

.github/workflows/tests.yml

@@ -63,7 +63,7 @@ jobs:
           sudo -u postgres psql -c "CREATE ROLE $PGUSER LOGIN SUPERUSER PASSWORD '$PGPASSWORD';"
 
       - name: Bundler cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: vendor/bundle
           key: ${{ runner.os }}-gem-${{ hashFiles('**/Gemfile.lock') }}
@@ -84,7 +84,7 @@ jobs:
         run: echo "::set-output name=dir::$(yarn cache dir)"
 
       - name: Yarn cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         id: yarn-cache
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}
@@ -104,7 +104,7 @@ jobs:
         run: bin/rake plugin:pull_compatible_all
 
       - name: Fetch app state cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         id: app-cache
         with:
           path: tmp/app-cache
@@ -216,7 +216,7 @@ jobs:
         run: echo "::set-output name=dir::$(yarn cache dir)"
 
       - name: Yarn cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         id: yarn-cache
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}