update tests to use Go 1.23

Author: bhcleek

.github/workflows/test.yml

@@ -27,7 +27,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go: ['1.21','1.22']
+        go: ['1.22','1.23']
         vim: ['vim-8.1', 'vim-8.2', 'nvim']
     steps:
     - name: setup Go