add 3.12.7 release notes (#1003)

What changed?

release note change
version change is no longer needed in gradle properties (auto selected once it's merged and tagged)
Why?

How did you test it?

tested 3.12.7-rc.1 with canary tests

Author: shijiesheng

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 3.12.7
+- Release use versions from git tags instead of static value (#1002)
+- support for testrunner for java in vscode (#1001)
+- Fix(RequestMapper): Correctly map all fields (#1000)
+- add github action for version releases to Sonatype (#996)
+
 ## 3.12.6
 - Adding logs to internal shadower to check for failures log (#918)
 - Removing fossa as it is migrated to snyk (#919)