feat: add support for opentofu v1.7 (#950)

Run tests for opentofu 1.7.x that was released in April:
https://github.com/opentofu/opentofu/releases/tag/v1.7.0

Author: jooola

.github/workflows/test.yml

@@ -44,6 +44,8 @@ jobs:
         include:
           - tool: opentofu
             version: v1.6.x
+          - tool: opentofu
+            version: v1.7.x
           - tool: terraform
             version: v1.8.x