docs(README): Remove python 2.7

See also: #306

Author: tony

README.rst

@@ -181,7 +181,7 @@ See donation options at https://git-pull.com/support.html.
 Project details
 ---------------
 - tmux support: 1.8, 1.9a, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6
-- python support: 2.7, >= 3.3, pypy, pypy3
+- python support: >= 3.5, pypy, pypy3
 - Source: https://github.com/tmux-python/libtmux
 - Docs: https://libtmux.git-pull.com
 - API: https://libtmux.git-pull.com/api.html