Log Message:
py-pkgconfig: update to 1.3.1.

Version 1.3.1
~~~~~~~~~~~~~

- Fix compatibility problems with Python 2.6

Version 1.3.0
~~~~~~~~~~~~~

- Add variables() API to query defined variables
- Disable Python 3.2 and enable Python 3.5 and 3.6 tests
- Fix #16: handle spaces of values in .pc files correctly