update ci to golang-1.16.5

Author: nonrational

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [macos-latest, macos-11.0, ubuntu-latest]
-        go-version: [1.15, 1.16.2]
+        go-version: [1.15, 1.16.5]
         ruby-version: [2.7]
 
     name: ${{ matrix.os }} / go-${{ matrix.go-version }}