fix: changes the tabIndex attribute to tabindex

[codebender828]

Description

fix: changes the tabIndex attribute to tabindex
fix: stack should be able to accept empty children

Motivation and Context

How Has This Been Tested?

Closes #454
Closes #425

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 2627e9f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@chakra-ui/vue	Patch
@chakra-ui/nuxt	Patch
chakra-ui-docs	Patch

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Sandbox	Source
Chakra UI Vue (0.X) Starter Template	Configuration
chakra-ui-nuxt-demo	Configuration
elastic-tereshkova-7bp5g	Issue #425