feat: add support for GH's pull_request_target

[aasseman]

GitHub defines 2 types of Pull Request events:

• pull_request
• pull_request_target

AFAIK, from dco-check's point of view, it does not make any difference, as in both cases the event_payload is the same.

[codecov[bot]]

Codecov Report

Merging #121 (b7dc2df) into master (9dd86e2) will decrease coverage by 1.38%. The diff coverage is 0.00%.

:exclamation: Current head b7dc2df differs from pull request most recent head 79840b1. Consider uploading reports for the commit 79840b1 to get more accurate results

@@            Coverage Diff             @@
##           master     #121      +/-   ##
==========================================
- Coverage   66.99%   65.61%   -1.39%     
==========================================
  Files           2        2              
  Lines         506      506              
  Branches       98       98              
==========================================
- Hits          339      332       -7     
- Misses        138      148      +10     
+ Partials       29       26       -3     

Impacted Files	Coverage Δ
dco_check/dco_check.py	65.47% <0.00%> (-1.39%)	:arrow_down:

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[aasseman]

Squashed the commits

[christophebedard]

I don't have access to a computer right now, but I'll try to make a new release soon.

[christophebedard]

I don't have access to a computer right now, but I'll try to make a new release soon.

Done!