Fix contributions.md / Grammer

Pronoun Problem

Author: NotMoni

contributions.md

@@ -120,5 +120,5 @@ The Laravel code of conduct is derived from the Ruby code of conduct. Any violat
 - Participants will be tolerant of opposing views.
 - Participants must ensure that their language and actions are free of personal attacks and disparaging personal remarks.
 - When interpreting the words and actions of others, participants should always assume good intentions.
-- Behavior which can be reasonably considered harassment will not be tolerated.
+- Behavior that can be reasonably considered harassment will not be tolerated.
 </div>