Remove legacy warning suppressions and Python 2 ignored collections.

conftest.py

@@ -37,10 +37,5 @@ def disable_coverage_on_pypy(config):
         cov.cov_controller.pause()
 
 
-if sys.version_info < (3,):
-    collect_ignore.append('setuptools/lib2to3_ex.py')
-    collect_ignore.append('setuptools/_imp.py')
-
-
 if sys.version_info < (3, 6):
     collect_ignore.append('pavement.py')

pytest.ini

@@ -9,17 +9,10 @@ filterwarnings =
     ignore:bdist_wininst command is deprecated
     # Suppress this error; unimportant for CI tests
     ignore:Extraction path is writable by group/others:UserWarning
-    # Suppress Python 2 deprecation warning
-    ignore:Setuptools will stop working on Python 2:UserWarning
     # Suppress weird RuntimeWarning.
     ignore:Parent module 'setuptools' not found while handling absolute import:RuntimeWarning
     # Suppress use of bytes for filenames on Windows until fixed #2016
     ignore:The Windows bytes API has been deprecated:DeprecationWarning
-    # Suppress other Python 2 UnicodeWarnings
-    ignore:Unicode equal comparison failed to convert:UnicodeWarning
-    ignore:Unicode unequal comparison failed to convert:UnicodeWarning
-    # https://github.com/pypa/setuptools/issues/2025
-    ignore:direct construction of .*Item has been deprecated:DeprecationWarning
     # https://github.com/pypa/setuptools/issues/2081
     ignore:lib2to3 package is deprecated:PendingDeprecationWarning
     ignore:lib2to3 package is deprecated:DeprecationWarning