ci: Remove cache_key calculation (#2299)

Refactor action.yml to remove RUBY_INPUT

Removed RUBY_INPUT from environment variables and simplified cache version handling.

Author: thompson-tomo

.github/actions/test_gem/action.yml

@@ -38,7 +38,6 @@ runs:
       shell: bash
       env:
         GEM_INPUT: ${{ inputs.gem }}
-        RUBY_INPUT: ${{ inputs.ruby }}
         LATEST_INPUT: ${{ inputs.latest }}
       run: |
         # 🛠️ Setup 🛠️
@@ -51,13 +50,6 @@ runs:
         # of the benefits of bundler caching.
         rm -f "${dir}/Gemfile.lock"
 
-        echo "cache_key=mri" >> $GITHUB_OUTPUT
-        if [[ "$RUBY_INPUT" == "jruby" ]]; then
-          echo "cache_key=jruby" >> $GITHUB_OUTPUT
-        elif [[ "$RUBY_INPUT" == "truffleruby" ]]; then
-          echo "cache_key=truffleruby" >> $GITHUB_OUTPUT
-        fi
-
         echo "appraisals=false" >> $GITHUB_OUTPUT
 
         if [[ "$LATEST_INPUT" != "true" ]]; then
@@ -93,7 +85,7 @@ runs:
         ruby-version: "${{ inputs.ruby }}"
         working-directory: "${{ steps.setup.outputs.gem_dir }}"
         bundler-cache: true
-        cache-version: "${{ inputs.ruby }}-${{ steps.setup.outputs.cache_key }}"
+        cache-version: "${{ inputs.ruby }}"
 
     # If we're using appraisals, do it all manually.
     - name: Install Ruby ${{ inputs.ruby }} without dependencies