The quopri module can convert those bytes to an unencoded byte stream. You need to then decode those from whatever character set they're in, then encode back to utf-8
.
>>> b = quopri.decodestring('=C4=EE=E1=F0=FB=E9 =E4=E5=ED=FC')
>>> print(b.decode('windows-1251'))
Добрый день