fix(NODE-5593): add repository field

[durran]

Description

Adds repository field to package.json

What is changing?

Add repository field, checked with npm run release -- --dry-run to verify:

> $ npm run release -- --dry-run                                                                      ⬡ 18.12.1 [±NODE-5593 ●]

> [email protected] release
> standard-version -a -i HISTORY.md --dry-run

✔ bumping version in package.json from 6.0.0 to 6.0.1
✔ bumping version in package-lock.json from 6.0.0 to 6.0.1
✔ outputting changes to HISTORY.md

---
### [6.0.1](https://github.com/mongodb-js/nodejs-mongodb-legacy/compare/v6.0.0...v6.0.1) (2023-10-12)
---

✔ committing package-lock.json and package.json and HISTORY.md and all staged files
✔ tagging release v6.0.1
ℹ Run `git push --follow-tags origin NODE-5593 && npm publish` to publish

Is there new documentation needed for these changes?

None

What is the motivation for this change?

NODE-5593

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket