don't install opencv deps

.github/workflows/cmake-multi-platform.yml

@@ -50,6 +50,7 @@ jobs:
     - uses: Dovyski/[email protected]
       with:
         opencv-version: '4.0.0'
+        install-deps: false
 
     - name: Set reusable strings
       # Turn repeated input strings (such as the build output directory) into step outputs. These step outputs can be used throughout the workflow file.