Merge branch '4.3' into 4.4

* 4.3:
  fix PHP 5.6 compatibility
  [Cache] fixed TagAwareAdapter returning invalid cache
  Add plus character `+` to legal mime subtype
  Make Symfony\Contracts\Service\Test\ServiceLocatorTest abstract
  bug #33942 [DI] Add extra type check to php dumper
  [Dotenv] search variable values in ENV first then env file
  [PropertyInfo] Respect property name case when guessing from public method name
  [VarDumper] fix resetting the "bold" state in CliDumper
  Missing argument in method_exists
  SCA: added missing break in a loop

FileBinaryMimeTypeGuesser.php

@@ -83,7 +83,7 @@ public function guessMimeType(string $path): ?string
 
         $type = trim(ob_get_clean());
 
-        if (!preg_match('#^([a-z0-9\-]+/[a-z0-9\-\.]+)#i', $type, $match)) {
+        if (!preg_match('#^([a-z0-9\-]+/[a-z0-9\-\+\.]+)#i', $type, $match)) {
             // it's not a type, but an error message
             return null;
         }