Better Windows support

[oyvindronningstad]

Should we add utf-8 encoding to

tests/unit/test3_float16/floats.py 16: with open(os.path.join(sys.argv[1], "fp_bytes_decode.bin"), 'wb') as f: 28: with open(os.path.join(sys.argv[1], "fp_bytes_encode.bin"), 'wb') as f:

and

tests/unit/test3_float16/floats.py 16: with open(os.path.join(sys.argv[1], "fp_bytes_decode.bin"), 'wb') as f: 28: with open(os.path.join(sys.argv[1], "fp_bytes_encode.bin"), 'wb') as f:

?

@hakonfam Those files are written as binary, so can't specify encoding. But I found one more instance in zcbor.py.