Drop Travis CI configuration

Travis CI stopped providing free CI services for open-source projects in
2020[1] and the last build happened more than two years ago[2].

[1]: https://www.travis-ci.com/blog/2020-11-02-travis-ci-new-billing/
[2]: https://app.travis-ci.com/github/SELinuxProject/selinux

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>

.travis.yml

@@ -1,14 +0,0 @@
-# Define the building environment
-language: c
-
-# Use Travis-CI Ubuntu 18.04 Bionic Beaver, "full image" variant
-sudo: required
-dist: bionic
-
-script:
-  - FEDORA_MAJOR=33 FEDORA_MINOR=1.2 scripts/ci/travis-kvm-setup.sh
-
-# Do not spam by email so long as the build succeeds
-notifications:
-  email:
-    on_success: never

README.md

@@ -116,7 +116,6 @@ This can be done using [./scripts/env_use_destdir](./scripts/env_use_destdir):
     DESTDIR=~/obj ./scripts/env_use_destdir make test
 
 Some tests require the reference policy to be installed (for example in `python/sepolgen`).
-In order to run these ones, instructions similar to the ones in section `install` of [./.travis.yml](./.travis.yml) can be executed.
 
 To install as the default system libraries and binaries
 (overwriting any previously installed ones - dangerous!),