Log Message:
py37-html-docs: Update to 3.7.3

Changes:
3.7.3
=====
Documentation
-------------
- bpo-36083: Fix formatting of --check-hash-based-pycs options in the
  manpage Synopsis.
- bpo-34764: Improve example of iter() with 2nd sentinel argument.
- bpo-21314: A new entry was added to the Core Language Section of the
  Programming FAQ, which explaines the usage of slash(/) in the signature of
  a function. Patch by Lysandros Nikolaou
- bpo-22062: Update documentation and docstrings for pathlib. Original patch
  by Mike Short.