Use parallel build in CI workflow

Add -j4 to make for faster compilation.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/main.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Build
         run: |
           export DEVKITPRO=/opt/devkitpro
-          make all
+          make -j4 all
         shell: bash
       - name: Upload artifact
         uses: actions/upload-artifact@v3