Merge branch '5.0'

* 5.0:
  [Dotenv] Documentation improvement
  [DI] Clarified deprecation for TypedReference in 4.4
  [Validator] Add missing vietnamese translations
  add German translation
  add missing Messenger options to XML schema definition
  [5.0] Remove some unused variables
  [Validator][ConstraintValidator] Update wrong PRETTY_DATE doc
  [DomCrawler][Form] Fix PHPDoc on get & offsetGet
  [ErrorHandler] fix parsing static return type on interface method annotation (fix #35836)
  prevent method calls on null values
  Return int if scale = 0

Author: fabpot

UnicodeString.php

@@ -241,7 +241,7 @@ public function replace(string $from, string $to): AbstractString
                 $tail = substr($tail, \strlen($slice) + \strlen($from));
             }
 
-            $str->string = $result .= $tail;
+            $str->string = $result.$tail;
             normalizer_is_normalized($str->string) ?: $str->string = normalizer_normalize($str->string);
 
             if (false === $str->string) {