chore(chain)!: use `debug_assert!` on `apply_update`

[oleonardolima]

fixes #1689

Description

As mentioned in issue #1689 the debug_assert! is being used on other LocalChain methods, such as: from_changeset, and apply_changeset but it was missing on apply_update.

Notes to the reviewers

Changelog notice

• Add usage of debug_assert!() to LocalChain::apply_update.

Checklists

All Submissions:

• [x] I've signed all my commits
• [x] I followed the contribution guidelines
• [x] I ran cargo fmt and cargo clippy before committing

New Features:

• [ ] I've added tests for the new feature
• [ ] I've added docs for the new feature

Bugfixes:

• [ ] This pull request breaks the existing API
• [ ] I've added tests to reproduce the issue which are now passing
• [ ] I'm linking the issue being fixed by this PR

[notmandatory]

oops I closed the wrong PR.