Merge branch '5.2' into 5.x

* 5.2:
  [Finder] Fix gitignore regex build with "**"
  Fixed deprecation warnings about passing null as parameter
  [Security] Keep Bulgarian wording consistent across all texts.
  Migrate configuration file for PHP CS Fixer 2.19/3.0
  [Form] Replace broken ServerParams mock
  [Mailer] Fix SES API call with UTF-8 Addresses

Author: fabpot

Firewall/UsernamePasswordJsonAuthenticationListener.php

@@ -79,8 +79,8 @@ public function __construct(TokenStorageInterface $tokenStorage, AuthenticationM
 
     public function supports(Request $request): ?bool
     {
-        if (false === strpos($request->getRequestFormat(), 'json')
-            && false === strpos($request->getContentType(), 'json')
+        if (false === strpos($request->getRequestFormat() ?? '', 'json')
+            && false === strpos($request->getContentType() ?? '', 'json')
         ) {
             return false;
         }