Revert "Cache always misses for tags, so save space and do not save back"

This reverts commit cc55f6015d.

.github/workflows/build.yml

@@ -42,7 +42,6 @@ jobs:
     - run: npm ci
     - name: Cache PlatformIO
       uses: actions/cache@v4
-      if: !startsWith(github.ref, 'refs/tags/')
       with:
         path: |
               ~/.platformio/.cache