Remove bot's response to repos missing @gitcoinbot

[arku]

Description

The gitcoinbot currently reacts with a heart emoji and a comment asking the maintainer to install gitcoinbot on the repo. The PR retains the heart emoji reaction and removes the comment.

Checklist

• linter status: 100% pass
• changes don't break existing behavior
• commit message follows commit guidelines

Refers/Fixes

Fixes #1498

[mbeacom]

lgtm! Thanks!

[codecov]

Codecov Report

Merging #1500 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1500      +/-   ##
==========================================
+ Coverage    28.3%   28.31%   +<.01%     
==========================================
  Files         125      125              
  Lines        9235     9233       -2     
  Branches     1188     1188              
==========================================
  Hits         2614     2614              
+ Misses       6524     6522       -2     
  Partials       97       97

Impacted Files	Coverage Δ
...itcoinbot/management/commands/get_notifications.py	0% <ø> (ø)	⬆️

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