fix: changing a request attribute data_type lead to an error

The data_type of `dynatrace_request_attribute` is immutable once created. The API rejected the request if the type changed. Therefore, adding a forceNew here, so that the resource is re-created if the data_type changes

Author: Kirdock

dynatrace/api/v1/config/requestattributes/settings/request_attribute.go

@@ -72,6 +72,7 @@ func (me *RequestAttribute) Schema() map[string]*schema.Schema {
 			Type:        schema.TypeString,
 			Description: "The data type of the request attribute",
 			Required:    true,
+			ForceNew:    true,
 		},
 		"normalization": {
 			Type:        schema.TypeString,