feat: Add command line argument for gyp --version

[cclauss]

Support will be difficult without this basic diagnostic capability.

DRY says we should not support the version number both in this file and setup.py

% gyp --version
v0.13.0

% gyp -V
v0.13.0

% gyp --help
usage: usage: gyp_main.py [options ...] [build_file ...]

options:
  -h, --help            show this help message and exit
  [ ... ]
  -V, --version         Show the version and exit.

[gengjiawen]

Can this be done reading https://github.com/nodejs/gyp-next/blob/main/setup.py ?
Currently auto release may not update this timely.

[cclauss]

The version number should not be stored in an executable file like setup.py but in a config file like pyproject.toml or setup.cfg. I will make that change...

[cclauss]

Shrink setup.py by adding setup.cfg. https://setuptools.pypa.io/en/latest/userguide/declarative_config.html

[targos]

Make sure to merge with a commit message starting with feat:. Then we can check if release-please works with this new setup.
For Python they need: