Force macos 11 (#14)

Author: ThadHouse

.github/workflows/ci.yml

@@ -111,7 +111,7 @@ jobs:
     env:
       MACOSX_DEPLOYMENT_TARGET: 10.14
     name: "Build - macOS"
-    runs-on: macos-latest
+    runs-on: macos-11
     steps:
       - uses: actions/checkout@v2
         with: