Drop compat for go 1.13-1.16

Author: knz

.github/workflows/ci.yaml

@@ -13,11 +13,10 @@ jobs:
     strategy:
       matrix:
         go:
-          - "1.13"
-          - "1.14"
-          - "1.15"
-          - "1.16"
           - "1.17"
+          - "1.18"
+          - "1.19"
+          - "1.20"
     steps:
     - uses: actions/checkout@v2