Update module github.com/prometheus/client_model to v0.6.1

vendor/google.golang.org/protobuf/reflect/protoreflect/methods.go

@@ -53,6 +53,7 @@ type (
 			FindExtensionByName(field FullName) (ExtensionType, error)
 			FindExtensionByNumber(message FullName, field FieldNumber) (ExtensionType, error)
 		}
+		Depth int
 	}
 	unmarshalOutput = struct {
 		pragma.NoUnkeyedLiterals