Update CI workflow to include Zig setup for cross-compilation

Author: GamePad64

.github/workflows/ci.yml

@@ -101,6 +101,7 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           key: ${{ matrix.target }}
+      - uses: mlugg/setup-zig@v2
       - uses: taiki-e/install-action@cargo-zigbuild
       - name: Build
         run: cargo zigbuild --release --target ${{ matrix.target }}