So, I tried to do some research about this. In most of the cases, they say to change the encoding to "latin-1" but it doesn't work for you.
You could try with encoding ='ISO-8859-1' or by opening it in "rb" so in binary mode. ( this is what internet sources say)
Although, I'm wondering how you got that error. The file itself is encoded in utf-8, I opened it just fine. i doubt that its encoded in another format. Did you remove the spaces before opening it? Perhaps, something you did modified the encoding of the file?