fix: loosen actor-matching check in Undo activity

public/language/en-GB/error.json

@@ -307,6 +307,5 @@
 	"activitypub.get-failed": "Unable to retrieve the specified resource.",
 	"activitypub.pubKey-not-found": "Unable to resolve public key, so payload verification cannot take place.",
 	"activitypub.origin-mismatch": "The received object's origin does not match the sender's origin",
-	"activitypub.actor-mismatch": "The received activity is being carried out by an actor that is different from expected.",
 	"activitypub.not-implemented": "The request was denied because it or an aspect of it is not implemented by the recipient server"
 }

src/activitypub/inbox.js

@@ -627,10 +627,6 @@ inbox.undo = async (req) => {
 	const { actor, object } = req.body;
 	const { type } = object;
 
-	if (actor !== object.actor) {
-		throw new Error('[[error:activitypub.actor-mismatch]]');
-	}
-
 	const assertion = await activitypub.actors.assert(actor);
 	if (!assertion) {
 		throw new Error('[[error:activitypub.invalid-id]]');