Checkout correctly and optionally select tag

.github/workflows/release.yml

@@ -6,8 +6,8 @@ on:
   workflow_dispatch:
     inputs:
       tag:
-        description: 'Tag to run CI on'
-        required: true
+        description: 'Optional tag to build'
+        required: false
 
 env:
   RUST_BACKTRACE: 0
@@ -62,6 +62,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+        with:
+          submodules: true
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@stable