Tweak shlex.quote comments based on picnixz's review

Try not to use don't and we're and should've etc apostrophes.

Author: jb2170

Lib/shlex.py

@@ -335,8 +335,8 @@ def quote(s, *, force=False):
                   b'abcdefghijklmnopqrstuvwxyz')
     if (not force
         and s.isascii() and not s.encode().translate(None, delete=safe_chars)):
-        # No quoting is needed if we're not forcing quoting
-        # and `s` is an ASCII string consisting only of `safe_chars`
+        # No quoting is needed if we are not forcing quoting
+        # and `s` is an ASCII string consisting only of `safe_chars`.
         return s
 
     # use single quotes, and put single quotes into double quotes