chore: update CHANGELOG to explain jump from 2.7.1 to 3.1.0.

Author: madpah

CHANGELOG.md

@@ -8,6 +8,8 @@
 * Out-factor SPDX compund detection ([`2b69925`](https://github.com/CycloneDX/cyclonedx-python-lib/commit/2b699252f8857d97231a689ea9cbfcdff9459626))
 * License factories ([`033bad2`](https://github.com/CycloneDX/cyclonedx-python-lib/commit/033bad2a50fd2236c712d4621caa57b04fcc2043))
 
+_Note: There was no 3.0.0 release officially, but due to CI publishing issues, an unexpected 3.0.0 release was publiched to PyPi and subsequently yanked from PyPi. There are NO breaking changes between 2.7.1 and 3.1.0._
+
 ## v2.7.1 (2022-08-01)
 ### Fix
 * BOM validation fails when Components or Services are nested [#275](https://github.com/CycloneDX/cyclonedx-python-lib/issues/275)