Deprecation warning due to invalid escape sequences.

[tirkarthi]

Describe the bug

Deprecation warning due to invalid escape sequences.

To Reproduce

find . -iname '*.py'  | xargs -P 4 -I{} python3.8 -Wall -m py_compile {}

./pvlib/iotools/ecmwf_macc.py:58: DeprecationWarning: invalid escape sequence \.
  """
./versioneer.py:485: DeprecationWarning: invalid escape sequence \s
  LONG_VERSION_PY['git'] = '''

[mikofski]

Thanks! It's in the docstring, there's a backwards path separator, you can see in the documentation, it doesn't render correctly, easy fix

[mikofski]

@tirkarthi seems okay now, can you please check again? Thx!

[tirkarthi]

versioneer file also needs usage of raw strings prefix.

[mikofski]

Versioneer is automatically generated, I think this issue has already been reported over there, Warner/python-versioneer: flake8 complaint #201