Update release notes for 2.1.4 (awslabs#244)

* Update release notes for 2.1.4

* remove commits at the end of PR url

* update the release date for 2.1.4

Author: vincentvilo-aws

README.md

@@ -146,6 +146,15 @@ all languages.
 
 ## Release Notes
 
+### Release 2.1.4 (April 23, 2024)
+* Upgraded KCL and KCL-Multilang dependencies from 2.5.2 to 2.5.8 [PR #239](https://github.com/awslabs/amazon-kinesis-client-python/pull/239)
+* Upgraded ion-java from 1.5.1 to 1.11.4 [PR #243](https://github.com/awslabs/amazon-kinesis-client-python/pull/243)
+* Upgraded logback version from 1.3.0 to 1.3.12 [PR #242](https://github.com/awslabs/amazon-kinesis-client-python/pull/242)
+* Upgraded io.netty dependency from 4.1.86.Final to 4.1.94.Final [PR #234](https://github.com/awslabs/amazon-kinesis-client-python/pull/234)
+* Upgraded Google Guava dependency from 32.0.0-jre to 32.1.1-jre [PR #234](https://github.com/awslabs/amazon-kinesis-client-python/pull/234)
+* Upgraded jackson-databind from 2.13.4 to 2.13.5 [PR #234](https://github.com/awslabs/amazon-kinesis-client-python/pull/234)
+* Upgraded protobuf-java from 3.21.5 to 3.21.7 [PR #234](https://github.com/awslabs/amazon-kinesis-client-python/pull/234)
+
 ### Release 2.1.3 (August 8, 2023)
 * Added the ability to specify STS endpoint and region [PR #221](https://github.com/awslabs/amazon-kinesis-client-python/pull/230)
 * Upgraded KCL and KCL-Multilang Dependencies from 2.5.1 to 2.5.2 [PR #221](https://github.com/awslabs/amazon-kinesis-client-python/pull/230)