Do not use the Fork Helper for tests

For nearly six months, the tests are falling regularly.
Fork is the only dependence, which is constantly fails tests
In the future we will deprecate the Fork Helper in favor of
ReactPHP, Promises, etc.

Cc: @duncan3dc

.travis.yml

@@ -47,9 +47,7 @@ before_install:
   - sudo ln -s /home/travis/.phpenv/versions/$(phpenv version-name)/bin/php-config /usr/bin/
   - export PHP_MAJOR="$(echo $TRAVIS_PHP_VERSION | cut -d '.' -f 1,2)"
   - if [[ ! -z "${GH_TOKEN}" ]]; then composer config github-oauth.github.com ${GH_TOKEN}; echo "Configured Github token"; fi;
-  # Install dev-dependencies
   - travis_retry composer install --prefer-dist --no-interaction --ignore-platform-reqs
-  - travis_retry composer require duncan3dc/fork-helper:$(if [[ "${PHP_MAJOR:0:1}" = "7" ]]; then echo "^2.0"; else echo "^1.0"; fi) --ignore-platform-reqs
 
 install:
   - ( bash tests/_ci/install_prereqs_$PHP_MAJOR.sh )