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

@@ -21,7 +21,7 @@
         "symfony/polyfill-mbstring": "^1.0"
     },
     "require-dev": {
-        "egulias/email-validator": "^2.0",
+        "egulias/email-validator": "^2.1.10",
         "symfony/dependency-injection": "^3.4|^4.1|^5.0"
     },
     "conflict": {