Add changelog for 0.42.0-rc1

CHANGELOG.md

+## 0.42.0-rc1 (2024-11-12)
+
+### Development (1 change)
+
+- [Support custom runner tag for image build job](https://gitlab.com/components/opentofu/-/commit/cfbc9d7950c7651f2cc0a551dfe52d623e19afb0) ([merge request](https://gitlab.com/components/opentofu/-/merge_requests/183))
+
 ## 0.41.0 (2024-11-12)
 
 ### Added (1 change)