Fix gitlab versioning errors with terraform 0.13

Author: dynamike

examples/gitlab-repository-webhook/README.md

@@ -21,7 +21,7 @@ Note that this example may create resources which cost money. Run `terraform des
 |------|---------|
 | <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 0.13.1 |
 | <a name="requirement_aws"></a> [aws](#requirement\_aws) | >= 3.45 |
-| <a name="requirement_gitlab"></a> [gitlab](#requirement\_gitlab) | >= 3.0 |
+| <a name="requirement_gitlab"></a> [gitlab](#requirement\_gitlab) | <= 3.20.0 |
 
 ## Providers
 

examples/gitlab-repository-webhook/versions.tf

@@ -8,8 +8,9 @@ terraform {
     }
 
     gitlab = {
+      # gitlab provider requires terraform 1.0 or later starting in 15.x.x
       source  = "gitlabhq/gitlab"
-      version = ">= 3.0"
+      version = "<= 3.20.0"
     }
   }
 }