Update buildtap.py

[peergine-admin]

No description provided.

[mattock]

@peergine-admin can you explain why this is useful/needed?

[peergine-admin]

When the non-default language is English type windows operation runtime, for example, the default character set of Chinese Windows operating system is GBK. Stupid python will report an error here.
UnicodeDecodeError: 'gbk' codec can't decode byte 0xbf in position 2: illegal multibyte sequence

[mattock]

@peergine-admin ok, I see. This does, however, break appveyor builds:

***** BUILD TAP config
Traceback (most recent call last):
  File "buildtap.py", line 511, in <module>
    btw.build()
  File "buildtap.py", line 280, in build
    self.build_tap()
  File "buildtap.py", line 255, in build_tap
    self.config_tap()
  File "buildtap.py", line 197, in config_tap
    self.preprocess(kv, os.path.join(self.src, "OemVista.inf"))
  File "buildtap.py", line 189, in preprocess
    with open(in_path+'.in', encoding='utf_8_sig') as f:
TypeError: 'encoding' is an invalid keyword argument for this function

Can you check what might be causing this?