[6.4] Allow 7.0 deps

Author: nicolas-grekas

composer.json

@@ -20,12 +20,12 @@
         "psr/container": "^1.1|^2.0",
         "symfony/deprecation-contracts": "^2.5|^3",
         "symfony/service-contracts": "^2.5|^3.0",
-        "symfony/var-exporter": "^6.2.10"
+        "symfony/var-exporter": "^6.2.10|^7.0"
     },
     "require-dev": {
-        "symfony/yaml": "^5.4|^6.0",
-        "symfony/config": "^6.1",
-        "symfony/expression-language": "^5.4|^6.0"
+        "symfony/yaml": "^5.4|^6.0|^7.0",
+        "symfony/config": "^6.1|^7.0",
+        "symfony/expression-language": "^5.4|^6.0|^7.0"
     },
     "conflict": {
         "ext-psr": "<1.1|>=2",