Fix CI test failures: update jest config, replace Box/Octicon, fix test assertions

Agent-Logs-Url: https://github.com/primer/doctocat/sessions/6f16c06f-1317-4086-9a54-f15e4b4566ce

Co-authored-by: francinelucca <40550942+francinelucca@users.noreply.github.com>

Author: Copilot

theme/src/components/__tests__/contributors.test.js

@@ -1,4 +1,4 @@
-import {render} from '@testing-library/react'
+import {render, screen} from '@testing-library/react'
 import React from 'react'
 import Contributors from '../contributors'
 
@@ -26,7 +26,7 @@ test('renders contributors', () => {
   debug()
   expect(queryByText(/2 contributors/)).toBeInTheDocument()
   expect(queryByText(/Last edited by/)).toBeInTheDocument()
-  expect(queryByText(/colebemis/)).toBeInTheDocument()
+  expect(screen.getAllByText(/colebemis/).length).toBeGreaterThan(0)
   expect(queryByText(/August 15, 2019/)).toBeInTheDocument()
 })