ci: drop older Go toolchains

Author: lucab

.github/workflows/go.yml

@@ -1,6 +1,6 @@
 ---
 name: Go
-on:
+"on":
   push:
     branches: [main]
   pull_request:
@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: ['1.14', '1.15', '1.16', '1.17', '1.18']
+        go: ['1.17', '1.18']
     steps:
       - run: sudo apt-get -qq update
       - name: Install libsystemd-dev