Nicer JSON output + exclude regex bug fix

[domanchi]

[ 658ad0d ]
It always annoyed me that the JSON output from scan had trailing whitespace. However, looks like this is an old, known issue, that only happens in < Python 3.4, and the fix is merely to add that line to it.

[ 0a6f767 ]
Fix to minor bug I discovered:

$ cat .secrets.baseline
{
  "exclude_regex": "^.secrets.baseline$",
  ...
}
$ detect-secrets scan --update .secrets.baseline
$ cat .secrets.baseline
{
  "exclude_regex": "^.secrets.baseline$|^.secrets.baseline",
  ...
}

[KevinHock]

LGTM

[KevinHock]

Squeaky clean commit history!