Update workflow to use Go 1.19 and Go 1.18 (#2525)

Author: gmlewis

.github/workflows/tests.yml

@@ -20,7 +20,7 @@ jobs:
       contents: read  # for actions/checkout to fetch code
     strategy:
       matrix:
-        go-version: [1.x, 1.17.x]
+        go-version: [1.x, 1.18.x]
         platform: [ubuntu-latest]
         include:
           # include windows, but only with the latest Go version, since there