github: make sure to init submodule

otherwise it fails to find nostrdb

.github/workflows/rust.yml

@@ -16,6 +16,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
+    - name: Initialize Submodules
+      run: git submodule update --init --recursive
     - name: Build
       run: cargo build --verbose
     - name: Run tests