Add macos-latest to workflow actions

This is a test commit to verify whether existing workflow actions can
run on macos-latest.

See opensearch-project/opensearch-build#38
for more details.

Signed-off-by: Michael Froh <froh@amazon.com>

.github/workflows/plugin_install.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest]
+        os: [ubuntu-latest, windows-latest, macos-latest]
         jdk: [11, 17]
     runs-on: ${{ matrix.os }}