chore: Update alpha version of TF mentioned in changelog (#1451)

Author: austinvalle

.changes/unreleased/NOTES-20250319-150717.yaml

@@ -1,5 +1,5 @@
 kind: NOTES
-body: This alpha pre-release contains an initial implementation for managed resource identity, which can used with Terraform v1.12.0-alpha20250312,
+body: This alpha pre-release contains an initial implementation for managed resource identity, which can used with Terraform v1.12.0-alpha20250319,
     to store and read identity data during plan and apply workflows. A managed resource identity can be used by defining an identity schema in the
     `resource.Identity` field. Once the identity schema is defined, you can read and store identity data in the new IdentityData struct that is available
     via the new `Identity()` method on ResourceData and ResourceDiff structs.