Make sure repos are updated before installing valgrind in CI

Author: saghul

.github/workflows/valgrind.yml

@@ -14,7 +14,7 @@ jobs:
         with:
           submodules: true
       - name: install valgrind
-        run: sudo apt-get install valgrind
+        run: sudo apt-get update && sudo apt-get install valgrind
       - name: build
         run: |
           make BUILD_TYPE=RelWithDebInfo