chore: preflight for 4.0.4 release (#789)

Author: rishav-karanjit

CHANGELOG.rst

@@ -2,6 +2,16 @@
 Changelog
 *********
 
+4.0.4 -- 2025-09-03
+===================
+
+Maintenance
+-----------
+* deps: Extend supported `MPL`_ versions to include v1.11.2
+  `#788 <https://github.com/aws/aws-encryption-sdk-python/pull/788>`_
+
+  MPL v1.11.2 fixes de-serializing Error_OpaqueWithText
+
 4.0.3 -- 2025-09-03
 ===================
 

src/aws_encryption_sdk/identifiers.py

@@ -17,7 +17,7 @@
     # We only actually need these imports when running the mypy checks
     pass
 
-__version__ = "4.0.3"
+__version__ = "4.0.4"
 USER_AGENT_SUFFIX = "AwsEncryptionSdkPython/{}".format(__version__)