Travis: Reduce build

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Author: methane

.travis.yml

@@ -3,20 +3,17 @@ dist: xenial
 language: python
 cache: pip
 arch:
-   - amd64
    - arm64
+
 python:
   # Available Python (PyPy) can be listed by:
   #
   #   $ aws s3 ls s3://travis-python-archives/binaries/ubuntu/16.04/x86_64/
-  - "3.4"
-  - "3.5"
   - "3.6"
   - "3.7"
   - "3.8"
   - "3.9-dev"
 
-
 _pure: &pure
   install:
     - pip install -U pip