Update constraints

composer.json

@@ -5,7 +5,7 @@
     "description": "Support for SEO metadata on products",
     "license": "MIT",
     "require": {
-        "php": "^7.2",
+        "php": "^7.2|^8.0",
         "sylius/sylius": "^1.4"
     },
     "require-dev": {
@@ -23,15 +23,15 @@
         "phpstan/phpstan-doctrine": "^0.10",
         "phpstan/phpstan-shim": "^0.10",
         "phpstan/phpstan-webmozart-assert": "^0.10",
-        "phpunit/phpunit": "^6.5",
+        "phpunit/phpunit": "^6.5 || ^9.0",
         "sensiolabs/security-checker": "^5.0",
         "sylius-labs/coding-standard": "^2.0",
-        "symfony/browser-kit": "^3.4|^4.1",
-        "symfony/debug-bundle": "^3.4|^4.1",
-        "symfony/dotenv": "^4.2",
-        "symfony/intl": "^3.4|^4.1",
-        "symfony/web-profiler-bundle": "^3.4|^4.1",
-        "symfony/web-server-bundle": "^3.4|^4.1"
+        "symfony/browser-kit": "^4.2 || ^5.0 || ^6.0",
+        "symfony/debug-bundle": "^4.2 || ^5.0 || ^6.0",
+        "symfony/dotenv": "^4.2 || ^5.0 || ^6.0",
+        "symfony/intl": "^4.2 || ^5.0 || ^6.0",
+        "symfony/web-profiler-bundle": "^4.2 || ^5.0 || ^6.0",
+        "symfony/web-server-bundle": "^4.2 || ^5.0 || ^6.0"
     },
     "conflict": {
         "symfony/symfony": "4.1.8",