Context
PyMongo 4.18.0 is ready to release. The changelog on main is complete but carries a placeholder release date (2026/XX/XX), and pymongo/_version.py is at 4.18.0.dev0.
Definition of done
- The changelog release date is set to 2026/09/03.
- A PR with the changelog date change is merged to main.
- The v4.18 release branch is cut and the 4.18.0 package is published.
Pitfalls
The create-release-branch.yml workflow bumps the version on the release branch via hatch version. Do not bump pymongo/_version.py to 4.18.0 in the PR; that would conflict with the workflow. The PR should touch only the changelog date, matching the 4.17 release (PYTHON-5801).