fix bom file encode error

[dongly]

In Windows 10 Simplified Chinese version, reading BOM files containing non-English characters (such as Chinese) will result in an error：

  File "e:\ProgramData\Miniconda3\Lib\site-packages\jlc_kicad_tools\jlc_lib\cpl_fix_rotations.py", line 69, in FixRotations
    for row in reader:
UnicodeDecodeError: 'gbk' codec can't decode byte 0xa8 in position 51: illegal multibyte sequence

[dongly]

45

Now, JLC is supported utf-8 file.

[matthewlai]

Thanks!