Merge branch '4.3' into 4.4

* 4.3:
  fix deps=low
  [VarExporter] fix support for PHP 7.4
  Use PHP 7.4 on deps=low

Author: nicolas-grekas

composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": "^7.1.3",
-        "egulias/email-validator": "^2.0",
+        "egulias/email-validator": "^2.1.10",
         "psr/log": "~1.0",
         "symfony/event-dispatcher": "^4.3",
         "symfony/mime": "^4.3.3|^5.0",