Add missing useMemo import

Author: koesie10

extensions/ql-vscode/src/view/method-modeling/MultipleModeledMethodsPanel.tsx

@@ -1,5 +1,5 @@
 import * as React from "react";
-import { useCallback, useState } from "react";
+import { useCallback, useMemo, useState } from "react";
 import { Method } from "../../model-editor/method";
 import { ModeledMethod } from "../../model-editor/modeled-method";
 import { styled } from "styled-components";