build: update CI test versions

Author: peakwinter

.travis.yml

@@ -1,14 +1,16 @@
 language: python
 python:
-  - "2.7"  # Everything
-  - "3.4"  # Debian 8 (Jessie) and Ubuntu 14.04 (Trusty)
-  - "3.5"  # Debian 9 (Stretch) and Ubuntu 16.04 (Xenial)
-  - "3.6"  # Debian 10 (Buster), Ubuntu 17.10 (Artful) & 18.04 (Bionic)
-  - "3.7-dev"  # Python alphas/betas
+  - "2.7"  # Legacy
+  - "3.5"  # Debian 9 (Stretch), Ubuntu 16.04 (Xenial)
+  - "3.6"  # Ubuntu 18.04 (Bionic)
+  - "3.7"  # Debian 10 (Buster), Ubuntu 17.10 (Artful)
+  - "3.8"  # Ubuntu 20.04 (Focal) and 20.10 (Groovy)
+  - "3.9"  # Debian 11 (Bullseye)
+  - "3.9-dev"  # Python alphas/betas
 
 matrix:
   fast_finish: true
   allow_failures:
-    - python: "3.7-dev"  # Alpha and beta versions can fail
+    - python: "3.9-dev"  # Alpha and beta versions can fail
 
 script: python tests.py