Pattern now matches fields with hyphens

The original pattern will miss fields like 'content-length', which is used in Pleroma's signature.

src/ActivityPhp/Server/Http/HttpSignature.php

@@ -28,7 +28,7 @@ class HttpSignature
             ([\w\-\.#\/@]+)
         )",
         (algorithm="(?P<algorithm>[\w\s-]+)",)?
-        (headers="\(request-target\) (?P<headers>[\w\s]+)",)?
+        (headers="\(request-target\) (?P<headers>[\w\s-]+)",)?
         signature="(?P<signature>[\w+\/]+={0,2})"
     /x';