refactor(aafig): Use hashlib library (sha1 deprecated since 2.5)

See also: https://docs.python.org/2.7/library/sha.html

Author: tony

docs/_ext/aafig.py

@@ -11,19 +11,14 @@
     :license: BOLA, see LICENSE for details
 """
 import posixpath
+from hashlib import sha1 as sha
 from os import path
 
 from docutils import nodes
 from docutils.parsers.rst.directives import flag, images, nonnegative_int
 from sphinx.errors import SphinxError
 from sphinx.util import ensuredir, logging, relative_uri
 
-try:
-    from hashlib import sha1 as sha
-except ImportError:
-    from sha import sha
-
-
 try:
     import aafigure
 except ImportError: