CI/Nix: build with submodules

- Clone repo recursively
- Update Nix install action
- Remove wlroots update

.github/workflows/nix-build.yml

@@ -18,12 +18,13 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: ${{ github.ref }}
+          submodules: recursive
 
-      - uses: cachix/install-nix-action@v25
+      - uses: cachix/install-nix-action@v26
       - uses: DeterminateSystems/magic-nix-cache-action@main
       - uses: cachix/cachix-action@v12
         with:
           name: hyprland
           authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
 
-      - run: nix build .#${{ matrix.package }} --extra-substituters "https://hyprland.cachix.org" -L
+      - run: nix build '.?submodules=1#${{ matrix.package }}' -L --extra-substituters "https://hyprland.cachix.org"