Use full clone in GitHub Actions

Configure actions/checkout to fetch the entire repository history instead of a shallow clone. This fixes the "shallow update not allowed" error when creating the repository database during releases.

The repo-db build step needs to push the entire repository to a temporary bare repo, which requires full history.

## Test plan

The error only occurs in CI with shallow clones. With fetch-depth: 0, the workflow will clone the full repository and the git push --mirror command will succeed.

Author: chrislloyd

.github/workflows/main.yml

@@ -24,6 +24,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - uses: mlugg/setup-zig@v2.0.1
         with: