Update changelog for upcoming 5.5.1 patch release

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 This changelog format was introduced in NAV 5.4.0. Older changelogs can be
 found in the [HISTORY](HISTORY) file.
 
+## [5.5.1] - 2022-11-09
+
+### Fixed
+
+- Delete and ignore module devices with fake serial number `BUILTIN`, as reported by Juniper equipment, in order to avoid spamming with `device[SFH]wUpgrade` alerts ([#2491](https://github.com/Uninett/nav/issues/2491), [#2492](https://github.com/Uninett/nav/pull/2492))
+
 ## [5.5.0] - 2022-11-04
 
 ### Changed