added new key point in changelog.md

Author: Manjusha.S

CHANGELOG.md

@@ -11,6 +11,7 @@ Magento Functional Testing Framework Changelog
 ### Fixes
 
 * Fixed incorrect MFTF test dependencies path
+* Removed PHP 7.3 build check from MFTF PR build as PHP 7.3 is no longer supported
 
 3.10.2
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