Add release notes for 1.3.12.0 (opensearch-project#3095)

### Description

Add release notes for 1.3.12.0

* Category (Enhancement, New feature, Bug fix, Test fix, Refactoring,
Maintenance, Documentation)

Documentation

### Check List
- [ ] New functionality includes testing
- [ ] New functionality has been documented
- [ ] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and
signing off your commits, please check
[here](https://github.com/opensearch-project/OpenSearch/blob/main/CONTRIBUTING.md#developer-certificate-of-origin).

Signed-off-by: Craig Perkins <cwperx@amazon.com>

release-notes/opensearch-security.release-notes-1.3.12.0.md

@@ -0,0 +1,9 @@
+## 2023-08-10 Version 1.3.12.0
+
+Compatible with OpenSearch 1.3.12
+
+### Maintenance
+
+* Bump BouncyCastle from jdk15on to jdk15to18 ([#2901](https://github.com/opensearch-project/security/pull/2901)) [#2931](https://github.com/opensearch-project/security/pull/2931)
+* Update guava to address CVE-2023-2976 ([#3060](https://github.com/opensearch-project/security/pull/3060))
+* Bump the version of kafka and spring-kafka-test (CVE Related) ([#3087](https://github.com/opensearch-project/security/pull/3087))