fix(deno): avoid crossing package boundary in deno-kv driver

[yxonic]

Use normalizeKey in "../utils" will cause problems. Check the built artifacts:

Before (BUG):

// drivers/deno-kv.mjs
import { normalizeKey } from "../utils";
import { defineDriver, createError } from "./utils/index.mjs";
...

After:

// drivers/deno-kv.mjs
import { defineDriver, createError, normalizeKey } from "./utils/index.mjs";
...