Fix v5.0.0 date in change log

[carmenbianca]

• [ ] Added a change log entry in changelog.d/<directory>/.
• [ ] Added self to copyright blurb of touched files.
• [ ] Added self to AUTHORS.rst.
• [ ] Wrote tests.
• [ ] Documented my changes in docs/man/ or elsewhere.
• [ ] My changes do not contradict the current specification.
• [x] I agree to license my contribution under the licenses indicated in the changed files.