net-im/toot: Update 0.50.1 => 0.51.0

Changelog:
https://github.com/ihabunek/toot/releases/tag/0.51.0

Remove TEST_DEPENDS since I couldn't test the port due to some ports
required for testing was conflicting with each other (cython and cython3
etc.). Also not all the required dependencies do exist in the tree.

PR: 290690