Bump terser and next

Bumps [terser](https://github.com/terser/terser) to 4.8.1 and updates ancestor dependency [next](https://github.com/vercel/next.js). These dependencies need to be updated together.


Updates `terser` from 4.6.13 to 4.8.1
- [Release notes](https://github.com/terser/terser/releases)
- [Changelog](https://github.com/terser/terser/blob/master/CHANGELOG.md)
- [Commits](terser/terser@v4.6.13...v4.8.1)

Updates `next` from 9.4.4 to 12.3.1
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v9.4.4...v12.3.1)

---
updated-dependencies:
- dependency-name: terser
  dependency-type: indirect
- dependency-name: next
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]