Fix regex for github tags

[frost19k]

GitHub tags generally begin with a 'v' - however the current regex (line 83) looks for a digit in the first character. This causes data (on line 90) to be assigned as an empty list.

The change also requires a modification to the input for the sorting algorithm on line 33. Note: stripping 'v' does nothing if 'v' doesn't exist in the input string.

[thelicato]

Thanks! We also need to update update our regex to be compatible with x.y.z-text (e.g. 2.0.0-beta) versions. Even though this creates a problem with the get_highest_version_number function. We'll figure it out.