DEV: Update actions cache keys for bundler and app cache (#26398)

Why this change?

Bundle cache should be keyed on ruby version as well as the debian
release name. Changes to the debian release can affect the way gems are
installed since gems may link to different versions of binaries.

.github/workflows/tests.yml

@@ -24,7 +24,7 @@ jobs:
     if: github.event_name == 'pull_request' || github.repository != 'discourse/discourse-private-mirror'
     name: ${{ matrix.target }} ${{ matrix.build_type }} # Update fetch-job-id step if changing this
     runs-on: ${{ (matrix.build_type == 'annotations') && 'ubuntu-latest' || 'ubuntu-20.04-8core' }}
-    container: discourse/discourse_test:slim${{ (matrix.build_type == 'frontend' || matrix.build_type == 'system') && '-browsers' || '' }}${{ (matrix.ruby == '3.1') && '-ruby-3.1.0' || '' }}
+    container: discourse/discourse_test:slim${{ (matrix.build_type == 'frontend' || matrix.build_type == 'system') && '-browsers' || '' }}
     timeout-minutes: 20
 
     env:
@@ -43,7 +43,6 @@ jobs:
       matrix:
         build_type: [backend, frontend, system, annotations]
         target: [core, plugins, themes]
-        ruby: ["3.2"]
         exclude:
           - build_type: annotations
             target: plugins
@@ -89,7 +88,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: vendor/bundle
-          key: ${{ runner.os }}-${{ matrix.ruby }}-gem-${{ hashFiles('**/Gemfile.lock') }}-cachev2
+          key: ${{ runner.os }}-${{ env.RUBY_VERSION }}-${{ env.DEBIAN_RELEASE }}-gem-${{ hashFiles('**/Gemfile.lock') }}-cachev2
 
       - name: Setup gems
         run: |