feat: drop support for terraform v1.7.x (#947)

Remove support for terraform v1.7.x which us now end-of-life:
https://endoflife.date/terraform

Author: jooola

.github/workflows/test.yml

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

README.md

@@ -8,7 +8,7 @@
 ## Requirements
 
 - [Terraform](https://developer.hashicorp.com/terraform/downloads)
-  - HashiCorp recommends to use the two latest terraform releases (1.7.x, 1.8.x). Our test suite validates that our provider works with these versions.
+  - HashiCorp recommends to use the two latest terraform releases (1.8.x). Our test suite validates that our provider works with these versions.
   - This provider uses the [terraform plugin protocol version 6](https://developer.hashicorp.com/terraform/plugin/terraform-plugin-protocol#protocol-version-6), and should work with all tools (ie. Terraform & OpenTofu) that supports it.
 - [Go](https://go.dev/doc/install) 1.21.x (to build the provider plugin)