www/py-gandi.cli: Update to 0.15 & Unbreak

• Update to 0.15
• Update RUN_DEPENDS version for click, (and patch setup.py accordingly) until upstream fixes it. [1].
• Make TEST_DEPENDS *only* include, test dependencies, adding RUN_DEPENDS instead to the TESTS option conditional.
• Remove non-compulsory & forced tests_requires. Tests work perfectly fine out of the box with setup:py:
  
  test_suite='gandi.cli.tests',

Changes:

https://github.com/Gandi/gandi.cli/blob/0.15/CHANGES.rst

[1] https://github.com/Gandi/gandi.cli/issues/147

Reported by: antoine, pkg-fallout (in that order)