Allow lower case names for SemVer `--increment`

[edgarrmondragon]

Description

The cz cli only accepts upper case increment names, but some tools work with lower case names for the same increment types. So, to keep things simpler in scripts, it'd be great to don't care about transforming to lower/upper case.

Possible Solution

Since decli is mostly a declarative wrapper around argparse, maybe a simple str.upper can be used as the type for increment.

This seems to work:

# rps.py
import argparse

parser = argparse.ArgumentParser()
parser.add_argument(
    'move',
    choices=['ROCK', 'PAPER', 'SCISSORS'],
    type=str.upper,
)

args = parser.parse_args()
print(args.move)

$ python rps.py rock     
ROCK

Additional context

I can submit a PR if this is desirable.

[woile]

Hey Edgar, that would be great! A PR is more than welcome