fix: spectify flutter-action version for workflow

Update prbuild.yml

.github/workflows/prbuild.yml

@@ -62,10 +62,12 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: subosito/flutter-action@v2
+      - uses: subosito/flutter-action@v2.12.0
         with:
           flutter-version: 3.16.8
           channel: stable
+      - name: Clear pubcache
+        run: flutter pub cache clean -f 
       - name: Install project dependencies
         run: flutter pub get
       - name: Build artifacts