travis-ci: Up from bionic to focal

sea5kg · sea5kg · commit dd9b0a7a71b9 · 2021-09-05T12:55:56.000+07:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,7 +4,7 @@ branches:
   only:
     - master
 
-dist: bionic
+dist: focal
 
 addons:
   apt:
