Remove boilerplate to run tests on PHP 8

.travis.yml

@@ -18,14 +18,7 @@ before_install:
 
 install:
     - travis_retry composer install
-    - |
+    - ./vendor/bin/simple-phpunit install
-      # install the phpunit-bridge with PHP 7.4 when testing nightly
-      if [[ $TRAVIS_PHP_VERSION = nightly ]]; then
-          (cd / && wget https://storage.googleapis.com/travis-ci-language-archives/php/binaries/ubuntu/16.04/x86_64/php-7.4.tar.bz2 -O - | tar -xj)
-          phpenv global 7.4;
-          ./vendor/bin/simple-phpunit install;
-          phpenv global nightly;
-      fi
 
 script: ./vendor/bin/simple-phpunit
 

composer.json

@@ -28,7 +28,7 @@
         "symfony/polyfill-ctype": "^1.8"
     },
     "require-dev": {
-        "symfony/phpunit-bridge": "^4.4|^5.0",
+        "symfony/phpunit-bridge": "^4.4.9|^5.0.9",
         "psr/container": "^1.0"
     },
     "autoload": {