chore: add terraform 1.8.x to test matrix (#229)

Author: johnstcn

.github/workflows/test.yml

@@ -54,6 +54,7 @@ jobs:
           - "1.5.*"
           - "1.6.*"
           - "1.7.*"
+          - "1.8.*"
     steps:
       - name: Set up Go
         uses: actions/setup-go@v5