Fixes errors such as
Traceback (most recent call last):
File "C:\Users\...\cairo\test\make-cairo-test-constructors.py", line 19, in <module>
for l in f.readlines():
File "c:\python39\lib\encodings\cp1253.py", line 23, in decode
return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x98 in position 6694: character maps to <undefined>
on non-English-language Windows locales/installations.
