Deprecate Python2.7. (#1153)

* deprecate Python2.7.

So we can use latest version of prompt-toolit.
Relate: https://github.com/dbcli/pgcli/pull/1149

* black format, remove 2.7 support.

* using version py35 for black.

* Revert "black format, remove 2.7 support."

This reverts commit 4b6d0496ccc18d0ebd696b5f21d8065c4a9b0cb9.

* deprecated py27 using black.

* remove 2.7 from travis.

* update setup.py: delete python 2.7 support.

1 files changed, 2 insertions, 0 deletions

diff --git a/README.rst b/README.rst
index 9e41867b..574e6e3e 100644
--- a/README.rst
+++ b/README.rst
@@ -281,6 +281,8 @@ choice:
 
     In [3]: my_result = _
 
+Pgcli only runs on Python3.6+ since 2.2.0, if you use an old version of Python,
+you should use install ``pgcli <= 2.2.0``.
 
 Thanks:
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