fix #905 - correct version file template for older python versions

[RonnyPfannschmidt]

closes #905

[andrewmwilson]

Thanks for the quick fix!

[RonnyPfannschmidt]

i have a pending fix for #906 as well then i will release 8.0.1

[maxnoe]

Having two type annotations in the same line is not even valid syntax in python 3.11.

So this fix is not only for "older python versions":

❯ cat test_annotations.py
__version__ : str = version : str = "foo"
❯ python --version
Python 3.11.4
❯ python test_annotations.py
  File "/home/maxnoe/Uni/CTA/ctapipe/test_annotations.py", line 1
    __version__ : str = version : str = "foo"
                                ^
SyntaxError: invalid syntax

Valid syntax would be to split the annotated variables into one instruction per line:

version: str = "foo"
__version__ : str = version