Allow installing on PHP 8.0 and test on travis using phpunit 9

Author: andypost

.travis.yml

@@ -40,6 +40,8 @@ matrix:
       env: SYMFONY_REQUIRE=4.4.*
     - php: 7.4
       env: SYMFONY_REQUIRE=5.0.*
+    - php: nightly
+      env: COMPOSER_FLAGS="--no-interaction --ignore-platform-reqs" SYMFONY_PHPUNIT_VERSION=9 SYMFONY_REQUIRE=5.0.*
   fast_finish: true
   allow_failures:
 

composer.json

@@ -15,7 +15,7 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^8.0",
         "symfony/routing": "^4.4 || ^5.0",
         "symfony/http-kernel": "^4.4 || ^5.0",
         "psr/log": "^1.0"