CI: remove cabal-head before updating it (fix haskell#10537)

Author: ulysses4ever

.github/workflows/validate.yml

@@ -473,8 +473,11 @@ jobs:
     needs: [validate, validate-old-ghcs, build-alpine, dogfooding]
 
     steps:
-      # for now this is hardcoded. is there a better way?
-      - uses: actions/download-artifact@v4
+    - uses: liudonghua123/delete-release-action@v1
+        with:
+          release_name: 'cabal-head'
+
+    - uses: actions/download-artifact@v4
         with:
           pattern: cabal-*
           path: binaries