Log Message:
Updated rspamd to 1.5.6.

1.5.6:
	* [Feature] Add unigramms support in bayes
	* [Feature] Allow configurable sign headers for DKIM
	* [Feature] Allow to add unigramm metatokens from Lua
	* [Feature] DKIM Signing: envelope match exception for local IPs
	* [Feature] UCL: register parser variables from Lua
	* [Fix] Always try to adjust filename
	* [Fix] Do extra copy to ensure that original content is never touched
	* [Fix] Fix SPOOF_REPLYTO rule
	* [Fix] Ignore Rmilter added Received
	* [Fix] More fixes for hashed email dnsbls
	* [Fix] Plug memory leak in chartable module
	* [WebUI] Display multiple alerts at once