chore: update checkout action to fetch submodules recursively

Author: ruslanti

.github/workflows/release-plz.yml

@@ -18,7 +18,7 @@ jobs:
         name: Checkout repository
         uses: actions/checkout@v5
         with:
-          fetch-depth: 0
+          submodules: recursive
           token: ${{ secrets.GITHUB_TOKEN }}
       - &install-rust
         name: Install Rust toolchain