Update python-sip to 4.19.7

Summary:

• The %Docstring directive can now include automatically generated signature descriptions using the "signature" option.
• typedefs can now have %Docstring directives.
• Bug fixes.

Signed-off-by: Pierre-Yves <pyu@riseup.net>

Test Plan: Build python3-sip, python-qt4 and python-qt5 against this version

Reviewers: Triage Team, sunnyflunk

Reviewed By: Triage Team, sunnyflunk

Differential Revision: https://dev.solus-project.com/D2098