Fix python build with debug binaries installed

[IlgarLunin]

Issue happens when you have debug libraries installed to python.

How to reproduce:

1. Install any python version INCLUDING DEBUG LIBRARIES
2. Clone tinyspline
3. Enable CXX and PYTHON targets
4. Run cmake
5. Obsereve cmake error: The "optimized" argument must be followed by a library
   

To overcome this, I moved LIBS argument of cmake_parse_arguments to multi_value_keywords instead of one_value_keywords arg.

Resulting target is linked to a proper dll, depending on current configuration:

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Didn't tested this change on other targets, but for python probably makes sense to start using FindPython2 and FindPython3 instead of deprecated FindPythonLibs

[msteinbeck]

Hi @IlgarLunin,

thank you very much for this PR. I'll have a look at your changes.

Didn't tested this change on other targets

The CI will show whether your changes break something.

but for python probably makes sense to start using FindPython2 and FindPython3 instead of deprecated FindPythonLibs

I'll have a look at this.

[msteinbeck]

Looks fine, thanks.

[IlgarLunin]

Thanks a lot for quick response 😺