Update autofill to 8.4.2

[daxmobile]

Task/Issue URL:
Autofill Release: https://github.com/duckduckgo/duckduckgo-autofill/releases/tag/8.4.2

Description

Updates Autofill to version 8.4.2.

Autofill 8.4.2 release notes

What's Changed

• Ema/perf followups by @GioSensation in Ema/perf followups duckduckgo-autofill#386
• Fix handler regression by @GioSensation in Fix handler regression duckduckgo-autofill#392
• Bump markdown-it from 13.0.1 to 13.0.2 by @dependabot in Bump markdown-it from 13.0.1 to 13.0.2 duckduckgo-autofill#388
• Revert mutation observer for forms by @GioSensation in Revert mutation observer for forms duckduckgo-autofill#396

Full Changelog: duckduckgo/duckduckgo-autofill@8.4.1...8.4.2

Steps to test

This release has been tested during autofill development. For smoke test steps see this task.

[kzar]

@GioSensation Annoyingly I can't reproduce the issue any more (with commit before your change), so it's hard to be 100% sure this has fixed it. But I also can't reproduce the issue with your changes, so I guess let's go ahead and merge for now and keep an eye on it.