[cairo] ANN: pycairo release 1.15.0 now available

[Christoph Reiter]

For more details see the changelog:

    https://pycairo.readthedocs.io/en/latest/changelog.html#v1-15-0

and for tarballs:

    https://github.com/pygobject/pycairo/releases/tag/v1.15.0