Don't overwrite cache

.forgejo/actions/prepare-rust/action.yaml

@@ -51,6 +51,7 @@ runs:
         export PATH=$PATH:$HOME/.rustup/bin
     -
       name: Populate rust cache
+      if: steps.cache.outputs.cache-hit != 'true'
       uses: https://github.com/actions/cache/save@v4
       with:
         path: |