[6.4] Allow 7.0 deps

Author: nicolas-grekas

composer.json

@@ -20,15 +20,15 @@
 "symfony/deprecation-contracts": "^2.5|^3",
 "symfony/polyfill-mbstring": "~1.0",
 "symfony/service-contracts": "^2.5|^3",
-"symfony/string": "^5.4|^6.0"
+"symfony/string": "^5.4|^6.0|^7.0"
  },
 "require-dev": {
-"symfony/config": "^5.4|^6.0",
-"symfony/event-dispatcher": "^5.4|^6.0",
-"symfony/dependency-injection": "^5.4|^6.0",
-"symfony/lock": "^5.4|^6.0",
-"symfony/process": "^5.4|^6.0",
-"symfony/var-dumper": "^5.4|^6.0",
+"symfony/config": "^5.4|^6.0|^7.0",
+"symfony/event-dispatcher": "^5.4|^6.0|^7.0",
+"symfony/dependency-injection": "^5.4|^6.0|^7.0",
+"symfony/lock": "^5.4|^6.0|^7.0",
+"symfony/process": "^5.4|^6.0|^7.0",
+"symfony/var-dumper": "^5.4|^6.0|^7.0",
 "psr/log": "^1|^2|^3"
  },
 "provide": {