Run pre-commit workflow with the latest runner, because ubuntu-20.04 is obsolete

Author: antonwolfy

.github/workflows/pre-commit.yml

@@ -13,7 +13,7 @@ on:
 
 jobs:
   pre-commit:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
     - uses: actions/setup-python@v2