Use ubuntu-20.04 for HIP CI

Author: WeiqunZhang

.github/workflows/hip.yml

@@ -13,7 +13,7 @@ concurrency:
 jobs:
   Tests:
     name: HIP Tests
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
     - uses: actions/checkout@v4
     - name: Dependencies