Update changelog for v0.18.1

Author: github-actions

CHANGELOG.md

@@ -10,6 +10,16 @@ See the changelog fragments in the [`changelog.d` directory](https://github.com/
 
 <!-- scriv-insert-here -->
 
+## 0.18.1 — 2021-07-24
+
+### Fixed
+
+- Changelog and release note generation as part of the release pipeline now works.
+
+### Added
+
+- All shell commands in the release pipeline now specify bash as the shell.
+
 ## 0.18.0 — 2021-07-24
 
 ### Added