End support for Python 2

As planned and advertized, yamllint drops support for Python 2 on 2021.

yamllint/linter.py

@@ -233,7 +233,7 @@ def run(input, conf, filepath=None):
     if conf.is_file_ignored(filepath):
         return ()
 
-    if isinstance(input, (type(b''), type(u''))):  # compat with Python 2 & 3
+    if isinstance(input, (bytes, str)):
         return _run(input, conf, filepath)
     elif hasattr(input, 'read'):  # Python 2's file or Python 3's io.IOBase
         # We need to have everything in memory to parse correctly

yamllint/rules/line_length.py

@@ -17,10 +17,6 @@
 """
 Use this rule to set a limit to lines length.
 
-Note: with Python 2, the ``line-length`` rule may not work properly with
-unicode characters because of the way strings are represented in bytes. We
-recommend running yamllint with Python 3.
-
 .. rubric:: Options
 
 * ``max`` defines the maximal (inclusive) length of lines.