Describe the bug

• Since fix(assert): check property equality up the prototype chain (#6151) #6153, assertEquals checks object prototypes. However, it makes certain exceptions to keep existing tests within the repo from failing.
• Other assertion libraries have more correct checks: "node:assert/strict", "ava", and "uvu" all make a distinction between null-prototype object and plain objects. "node:assert" and "chai" don't.

Steps to Reproduce
The following assertion passes:

import { assertEquals } from "@std/assert"
assertEquals(Object.create(Object.prototype), Object.create(null))

Expected behavior
The assertion fails.

Environment
Not applicable.