GHA: Update checkout action to v3

Author: stchris

.github/workflows/build.yml

@@ -11,7 +11,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
       - name: Set up
         run: |
           docker --version