Merge branch '6.4' into 7.3

* 6.4:
  [Cache] Fix accepting named closures as early-expiration callbacks
  [Mime] Update mime types
  [Yaml] Align unquoted multiline scalar parsing with spec for comments
  work around limitation in JsonResponse when the data is null
  do not use recipient phone numbers as sender e-mail addresses
  [Dotenv] DotenvDumpCommand cannot be internal

Author: nicolas-grekas