ci: 统一使用 ubuntu 24.04 运行 ci（20.04 将被弃用） (#271)

.github/workflows/pr-check.yaml

@@ -20,7 +20,7 @@ env:
 jobs:
   tests:
     name: Run Clippy and tests
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     if: ${{ github.event_name == 'push' || !github.event.pull_request.draft }}
     steps:
       - name: Checkout repo