Import version from setuptools_scm generated file

[coretl]

We already have a generated version file, so we might as well use it.

https://github.com/DiamondLightSource/python-copier-template/blob/0dcd88b75b6df04bfe92a432ca0c0376af9f37f8/template/src/%7B%7B%20package_name%20%7D%7D/__init__.py.jinja#L1-L11

Can be changed to:

from ._version import __version__

__all__ = ["__version__"]

And the file renamed to __init__.py

We can also lose the dependency on typing_extensions, so

https://github.com/DiamondLightSource/python-copier-template/blob/0dcd88b75b6df04bfe92a432ca0c0376af9f37f8/template/pyproject.toml.jinja#L17-L19

becomes:

dependencies = [] # Add project dependencies here, e.g. ["click", "numpy"]