travis-ci: remove Ubuntu Eoan

Ubuntu Eoan is EOL and fails in CI on apt repositories updating with
'does not have a Release file' errors.

Author: LeonidVas

.travis.yml

@@ -104,8 +104,6 @@ jobs:
       env: OS=ubuntu DIST=xenial
     - <<: *packpack
       env: OS=ubuntu DIST=bionic
-    - <<: *packpack
-      env: OS=ubuntu DIST=eoan
     - <<: *packpack
       env: OS=ubuntu DIST=focal
     - <<: *packpack