fix: set upper bound on datadog provider to < 4.0.0 (#104)

The datadog/datadog provider v4.0.0 removed the
`datadog_integration_aws_lambda_arn` and
`datadog_integration_aws_log_collection` resource types, breaking
this component. Pin to < 4.0.0 until the component is updated to
use the replacement resources.

Follows up on #103 which removed the AWS provider upper bound.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: wavemoran

src/versions.tf

@@ -8,7 +8,7 @@ terraform {
     }
     datadog = {
       source  = "datadog/datadog"
-      version = ">= 3.3.0"
+      version = ">= 3.3.0, < 4.0.0"
     }
   }
 }