Merge pull request #797 from bettio/remove-old-dot-travis

Remove .travis.yml

It has been unused for quite a long time, so let's remove it.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later