ci: setup ninja through aseprite/get-ninja action

.github/workflows/main.yml

@@ -50,7 +50,7 @@ jobs:
           ${{ matrix.platform.msys-env }}-libwebp
           ${{ matrix.platform.msys-env }}-zlib
     - name: Install Ninja
-      uses: turtlesec-no/get-ninja@main
+      uses: aseprite/get-ninja@main
       if: ${{ !contains(matrix.platform.shell, 'msys2') }}
     - name: Set up SDL
       id: sdl