Remove travis integration

.travis.yml

@@ -1,71 +0,0 @@
-language: php
-dist: xenial
-sudo: false
-
-php:
-  - '5.6'
-  - '7.1'
-  - '7.2'
-  - '7.3'
-  - '7.4'
-  - nightly
-
-env:
-  - CHECK=phpunit
-
-matrix:
-  include:
-    - env: CHECK=phpcs
-      php: '7.4'
-    - env: CHECK=phpcs
-      php: '7.3'
-    - env: CHECK=phpcs
-      php: '7.2'
-    - env: CHECK=phpcs
-      php: '7.1'
-    - env: CHECK=phpcs
-      php: '5.6'
-    - env: CHECK=syntax
-      php: 'nightly'
-    - env: CHECK=syntax
-      php: '7.4'
-    - env: CHECK=syntax
-      php: '7.3'
-    - env: CHECK=syntax
-      php: '7.2'
-    - env: CHECK=syntax
-      php: '7.1'
-    - env: CHECK=syntax
-      php: '5.6'
-  allow_failures:
-    - php: nightly
-
-services:
-  - mysql
-  - postgresql
-
-cache:
-  directories:
-    - vendor
-
-branches:
-  only:
-  - master
-  - /^v\d/
-
-notifications:
-  email: false
-
-# also see: test/setup_vendor.sh
-before_script:
-  - php -m
-  - '[ -z $LOCALE_GEN ] || sudo locale-gen en_US.UTF-8 de_DE.UTF-8 fr_FR.UTF-8'
-  - '[ -z $ENABLE_LDAP ] || phpenv config-add test/travis-ldap.ini'
-  - test/setup_vendor.sh
-  - 'if [ "$CHECK" = phpunit ]; then test/travis_database.sh; fi'
-
-script:
-  # also see: modules/test/application/clicommands/PhpCommand.php
-  - 'if [ "$CHECK" = phpcs ]; then php vendor/phpcs.phar; fi'
-  - 'if [ "$CHECK" = phpunit ]; then php vendor/phpunit.phar -c modules/test/phpunit.xml --verbose; fi'
-  - 'if [ "$CHECK" = syntax ]; then php test/check-syntax.php -e "^(\./)?vendor/" -e Icinga/Util/String.php; fi'