Upgrade to latest flutter_gherkin and gherkin

[SleepySquash]

Synopsis

gherkin is a package used for E2E tests. The currently used package is outdated.

Solution

This PR upgrade flutter_gherkin and gherkin.

Checklist

• Created PR:
  • In draft mode
  • Name contains issue reference
  • Has type and k:: labels applied
• Before review:
  • Documentation is updated (if required)
  • Tests are updated (if required)
  • Changes conform code style
  • CHANGELOG entry is added (if required)
  • FCM (final commit message) is posted or updated
  • Draft mode is removed
• Review is completed and changes are approved
  • FCM (final commit message) is approved
• Before merge:
  • Milestone is set
  • PR's name and description are correct and up-to-date
  • All temporary labels are removed

[SleepySquash]

Problems found so far: neither macOS nor Chrome E2E tests work. There seems to be a really large lags and stutters during E2E tests which are the reason view doesn't get updated and steps don't complete.

[SleepySquash]

Discussed alternative: if we won't be able to determine the reason as to why tests fail on the latest flutter_gherkin version, then we can fork the older commit and upgrade dependencies there.

[SleepySquash]

Currently using a fork: https://github.com/SleepySquash/flutter_gherkin/commits/upgrade-packages/