Remove comma from simple entries w/o given reason (#1322)

* Remove comma from simple entries w/o given reason

- Remove the comma at the end of simple entries without given reason.
  Use the following command to find these entries:
  awk -F , 'NF == 2' < ./codespell_lib/data/dictionary.txt | \
  grep --invert disabled
- Output was:
  inteligable->intelligible,
  inturpratasion->interpretation,
  invokable->invocable,
  lightsensor->light sensor,
  won;t->won't,

* Add test for simple entries with trailing comma

* MAINT: Use regex