Remove macOS-latest from GitHub Actions config.

Author: rwjblue

.github/workflows/ci.yml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       matrix:
         node: ['10', '12', '14']
-        os: [ubuntu-latest, macOS-latest]
+        os: [ubuntu-latest]
 
     steps:
     - uses: actions/checkout@v1