Update ci.yml

Author: ViralBShah

.github/workflows/ci.yml

@@ -32,5 +32,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - uses: msys2/setup-msys2@v2
+      with: 
+        msystem: MINGW64
     - run: make
     - run: make test