Revert "python3: avoid hardcode of arbitrary python version"

This reverts commit 7f136b0.

Author: ligurio

.travis.yml

@@ -1,13 +1,5 @@
 language: python
-
-python:
-  - "2.7"
-  - "3.4"
-  - "3.5"
-  - "3.6"
-  - "3.7"
-  - "3.8"
-  - "3.8-dev"
+python: 2.7
 
 before_install:
   - sudo apt update -y

Makefile

@@ -5,7 +5,7 @@ default:
 lint: flake8 luacheck
 
 flake8:
-	python -m flake8 *.py lib/*.py
+	python2 -m flake8 *.py lib/*.py
 
 luacheck:
 	luacheck --config .luacheckrc .

test-run.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 """Tarantool regression test suite front-end."""
 
 from __future__ import absolute_import