Merge branch '5.2' into 5.x

* 5.2:
  [Notifier] Prepare bridges for the upcoming return type change.

Author: nicolas-grekas

composer.json

@@ -18,7 +18,7 @@
     "require": {
         "php": ">=7.2.5",
         "symfony/http-client": "^4.3|^5.0",
-        "symfony/notifier": "^5.3"
+        "symfony/notifier": "~5.3.0"
     },
     "autoload": {
         "psr-4": { "Symfony\\Component\\Notifier\\Bridge\\LinkedIn\\": "" },