handle warning in newer pandas version

[mattmilten]

We currently get a warning with newer pandas versions:

grblogtools\helpers.py:47: FutureWarning: Not prepending group keys to the result index of transform-like apply. In the future, the group keys will be included in the index, regardless of whether the applied function returns a like-indexed object.
To preserve the previous behavior, use

	>>> .groupby(..., group_keys=False)

To adopt the future behavior and silence this warning, use 

	>>> .groupby(..., group_keys=True)
  return parameters.groupby("Version").apply(fill_for_version_nosuffix)

I added the suggested group_keys=False to the two affected calls of groupby() to avoid this warning.

[CLAassistant]

All committers have signed the CLA.

[simonbowly]

Looks good, group_keys=False is what we want here. Thanks!

[mattmilten]

@simonbowly, do you have any idea why those checks are failing?

[simonbowly]

They're failing on master as well. It looks like poetry has an issue with isort, and we need to upgrade it: PyCQA/isort#2077

[simonbowly]

Merging #31 should fix the problem here

[simonbowly]

I merged #31 and rebased this. All good now