removed support for older Python versions

.travis.yml

@@ -1,8 +1,5 @@
 language: python
 python:
-    - "2.7"
-    - "3.4"
-    - "3.5"
     - "3.6"
     - "3.7"
     - "3.8"

README.md

@@ -75,6 +75,5 @@ Useful links
 Dependencies
 ------------
 
- - Python 2.7 (tested on 2.7.9; 2.6 might work, but test suite lacks support)
-   or 3.x (tested on 3.2, 3.3, 3.4 and 3.5)
+ - Python 3.5 or later
  - Python Imaging Library (Debian/Ubuntu package: `python-imaging`)