ci: add testing with 1.16/1.17/1.18

Author: miabbott

.github/workflows/go.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: ['1.14', '1.15']
+        go: ['1.14', '1.15', '1.16', '1.17', '1.18']
     steps:
       - run: sudo apt-get -qq update
       - name: Install libsystemd-dev