Use Python 3.8 nox environment for lint checks

Signed-off-by: Nabarun Pal <[email protected]>

Author: palnabarun

.travis.yml

@@ -20,7 +20,7 @@ jobs:
   include:
     # Basic Checks
     - stage: primary
-      env: NOXSESSION=lint-3.5
+      env: NOXSESSION=lint-3.8
     - env: NOXSESSION=test-2.7
     - env: NOXSESSION=test-3.5
     - env: NOXSESSION=docs