Update WordPress-Editor-iOS version to 1.19.6

[geriux]

This PR updates the WordPress-Editor-iOS version to 1.19.6 needed by the latest version of Gutenberg.

To test CI checks should pass

Regression Notes

1. Potential unintended areas of impact
   It's a new formatting feature within the editor that shouldn't affect any other areas.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manual testing in the Gutenberg implementation.

3. What automated tests I added (or what prevented me from doing so)
   N/A

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

	Warnings
⚠️	PR is not assigned to a milestone.

Generated by 🚫 dangerJS

[guarani]

Changes look good to me, thanks @geriux!

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.