Merge pull request #98 from isudana/master

Update build matrix to only use Ubuntu

Author: isudana

.github/workflows/build_pull.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest]
         java: [8, 11]
 
     steps: