doc: release notes 1.3.1

Signed-off-by: Jaime Silvela <[email protected]>

Author: jsilvela

DEVELOPERS_DEVELOPERS_DEVELOPERS.md

@@ -97,6 +97,7 @@ before cutting out a new release.
 See the [GitHub document on using third party actions](https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions).
 
 Example:
+
 ``` yaml
       - name: Compute the E2E test summary
         id: generate-summary

ReleaseNotes.md

@@ -6,6 +6,15 @@ For a complete list of changes, please refer to the
 [commits](https://github.com/cloudnative-pg/ciclops/commits/main)
 on the `main` branch in GitHub.
 
+## Version 1.3.1
+
+**Release date:** Nov 25, 2024
+
+Improvements:
+
+- Use `floor` rather than `round` in the thermometer, so that we don't get 100%
+  success in the presence of failures (#15)
+
 ## Version 1.3.0
 
 **Release date:** Jun 06, 2024