Merge branch '4.3' into 4.4

* 4.3:
  Bump minimal requirements

Author: nicolas-grekas

composer.json

@@ -26,7 +26,7 @@
         "symfony/expression-language": "^3.4|^4.0|^5.0",
         "symfony/http-foundation": "^3.4|^4.0|^5.0",
         "symfony/ldap": "^4.4|^5.0",
-        "symfony/validator": "^3.4|^4.0|^5.0",
+        "symfony/validator": "^3.4.31|^4.3.4|^5.0",
         "psr/log": "~1.0"
     },
     "conflict": {