Cache scalafmt unconditionally

It does not matter whether scalafmt passes or fails,
we want to cache scalafmt if we downloaded it.

action.yml

@@ -22,18 +22,26 @@ runs:
       ${{ github.action_path }}/set-path.sh
     env:
       scalafmt_version: ${{ inputs.version }}
-  - uses: actions/cache@v3
+  - uses: actions/cache/restore@v4
     id: cache
     with:
       path: ${{ env.SCALAFMT_PATH }}
       key: scalafmt-${{ inputs.version }}
   - shell: bash
+    id: retrieve-scalafmt
     if: ${{ !steps.cache.outputs.cache-hit }}
     run: |
       curl -sL https://github.com/scalameta/scalafmt/releases/download/v${scalafmt_version}/scalafmt-linux-glibc > "$SCALAFMT_PATH/scalafmt"
       chmod +x "$SCALAFMT_PATH/scalafmt"
+      echo "retrieved=1" >> "$GITHUB_OUTPUT"
   - shell: bash
     run: |
       ${{ github.action_path }}/run-scalafmt.sh
     env:
       args: ${{ inputs.args }}
+  - name: Cache scalafmt
+    if: ${{ always() && steps.cache.retrieve-scalafmt.retrieved }}
+    uses: actions/cache/save@v4
+    with:
+      path: ${{ env.SCALAFMT_PATH }}
+      key: scalafmt-${{ inputs.version }}