Update dependencies

[katjuell]

What should this PR do?

Resolves DEVED-93 by bumping versions of js-yaml, next-mdx-remote, rehype-react, remark-rehype, and sass.

This PR does not bump rehype-slug or rehype-autolink-headings due to low current adoption of these packages currently (in each case, a Sourcegraph search results in only one instance of adoption for these versions in 1M repos), coupled with the update being a breaking change.

Some context for future discussion of adopting these packages:
rehype-slug rewrite
next-mdx-remote type definitions, particularly for mdxOptions
Open issue on types for remarkPlugins and rehypePlugins in next-mdx-remote.

Why are we making this change?

• Part of an effort to keep our dependencies up-to-date

What are the acceptance criteria?

• The app should exhibit no changes, and builds should succeed.

How should this PR be tested?

• Check out the branch, remove node_modules, and install dependencies with npm ci.
• Ensure that the above criteria are met.

Pull request process

Reviewers:

1. Test functionality using the criteria above.
2. Offer tips for efficiency, feedback on best practices, and possible alternative approaches and things that may not have been considered.
3. For shorter, "quick" PRs, use your best judgement on #​2.
4. Use a collaborative approach and provide resources and/or context where appropriate.
5. Provide screenshots/grabs where appropriate to show findings during review.

Reviewees:

1. Prefer incremental and appropriately-scoped changes.
2. Leave a comment on things you want explicit feedback on.
3. Respond clearly to comments and questions.

[netlify]

✔️ Deploy Preview for sourcegraph-learn ready!

🔨 Explore the source changes: 03f9c57

🔍 Inspect the deploy log: https://app.netlify.com/sites/sourcegraph-learn/deploys/611a8a279f964d000809e2a3

😎 Browse the preview: https://deploy-preview-168--sourcegraph-learn.netlify.app

[katjuell]

Will close #149 and #148 manually once this is merged.

[ltagliaferri]

Thanks, Katy, everything working as expected. Would like to hear more about the other dependencies once you have more thoughts / recommendations / learn more about how others are going about it.