fix: broken pull_requests.json

[henry-p]

Problem

This FAILS:

# x.py to test

import json

with open("tap_github/schemas/pull_requests.json") as json_data:
    json.load(json_data)

=>

Traceback (most recent call last):
  File "x.py", line 6, in <module>
    x = json.load(json_data)
  File "/usr/local/anaconda3/lib/python3.7/json/__init__.py", line 296, in load
    parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
  File "/usr/local/anaconda3/lib/python3.7/json/__init__.py", line 348, in loads
    return _default_decoder.decode(s)
  File "/usr/local/anaconda3/lib/python3.7/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/anaconda3/lib/python3.7/json/decoder.py", line 353, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 97 column 5 (char 2073)

Proposed changes

Fixing trailing comma.

Types of changes

What types of changes does your code introduce to PipelineWise?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

[henry-p]

@teaf-wise this error was introduced with the last merged PR approved by you. Would be great if you could take a quick look, as we'd like to be able to use this new version. Currently, when using this version within Pipelinewise, it simply doesn't work due to the bug.