Reword changelog

Author: mamercad

CHANGELOG.rst

@@ -8,7 +8,7 @@ Python 3.6 is no longer supported; Stackstorm requires at least Python 3.8.
 
 Fixed
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-* Restore Pack integration testing. #6135
+* Restore Pack integration testing (it was inadvertently skipped) and stop testing against `bionic` and `el7`. #6135
 
 Changed
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