Merge branch '3.4' into 4.3

* 3.4:
  Add plus character `+` to legal mime subtype
  [Dotenv] search variable values in ENV first then env file
  [VarDumper] fix resetting the "bold" state in CliDumper
  SCA: added missing break in a loop

Author: nicolas-grekas

FileBinaryMimeTypeGuesser.php

@@ -85,7 +85,7 @@ 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;
         }