Apply ruff/pyupgrade rule UP009

UP009 UTF-8 encoding declaration is unnecessary

Author: DimitriPapadopoulos

doc/source/conf.py

@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-#
 # CFFI documentation build configuration file, created by
 # sphinx-quickstart on Thu Jun 14 16:37:47 2012.
 #

src/cffi/recompiler.py

@@ -1315,10 +1315,6 @@ def _print_string_literal_in_array(self, s):
             s = s.encode('utf-8')       # -> bytes
         else:
             s.decode('utf-8')           # got bytes, check for valid utf-8
-        try:
-            s.decode('ascii')
-        except UnicodeDecodeError:
-            s = b'# -*- encoding: utf8 -*-\n' + s
         for line in s.splitlines(True):
             comment = line
             if type('//') is bytes:     # python2