Add checkout phase

Author: angerman

.github/workflows/x86_64-linux.yml

@@ -7,6 +7,9 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+
     - name: Run Prebuild Workflow for x86_64-linux
       uses: ./.github/workflows/main.yml
       with: