Update aries_cloudagent/wallet/default_verification_key_strategy.py

added multikey support

Co-authored-by: Patrick St-Louis <43082425+PatStLouis@users.noreply.github.com>
Signed-off-by: Aritra Bhaduri <92646038+aritroCoder@users.noreply.github.com>

aries_cloudagent/wallet/default_verification_key_strategy.py

@@ -75,7 +75,7 @@ async def get_verification_method_id_for_did(
             did_resolver = profile.inject(DIDResolver)
             did_document = await did_resolver.resolve(profile=profile, did=did)
             if proof_type:
-                verification_method_type = self.key_types_mapping[proof_type]
+                verification_method_types = self.key_types_mapping[proof_type]
                 verification_method_list = did_document.get("verificationMethod", None)
                 for method in verification_method_list:
                     if method.get("type") == verification_method_type: