Validation fails when h= tag contains FWS

[jhammer]

The DKIM spec allows for FWS on either side of the colon separator in the list of header field names for the “h=“ tag. For example:

DKIM-Signature: v=1; a=rsa-sha256; s=redacted; d=redacted; t=1644958961; 
	i=redacted; c=relaxed/relaxed; h=from: 
	list-unsubscribe: date: subject: to: message-id: mime-version: content-type; 
	bh=V9a5m8Ke5J2on4sGERXxG4eaO8kvRsAa3l7fx6Z2YRA=; 
	b=q0yRyQptqx7H3336GDVm93oIvZE9gXO/mIx78Y7FgxHILCzWN7i/JeyLP0/dhkPEwN63YNGEFkVg
	peLr8qnahyQCEyixh/hrCUx24926xzNqDyu1ijVjI4o/PWE1waRskvjVVHqfpZfkERrQJOZQzsfTiH
	sS/A90Z8DiFMJuPUY=

Unfortunately, DKIMValidator fails to validate signatures with FWS on either side of the colon separator.