Fix action

.github/actions/appraisal-install/action.yml

@@ -8,6 +8,7 @@ runs:
   using: "composite"
   steps:
     - name: Copy lockfile
+      shell: bash
       run: bundle exec ${{ inputs.appraisal }} "cp $BUNDLE_GEMFILE.lock current_appraisal.gemfile.lock"
     - name: Appraisal package cache
       uses: actions/cache@v4
@@ -18,4 +19,5 @@ runs:
           v6-gem-cache-${{ runner.os }}-${{ github.ref }}-
           v6-gem-cache-${{ runner.os }}-
     - name: Install appraisal dependencies
+      shell: bash
       run: bundle exec appraisal ${{ inputs.appraisal }} bundle install --jobs=1 --retry=3 --path=../vendor/bundle