AMP error if admin bar styles are removed

### Bug Description

If visiting a wordpress page where I removed admin bar styles, AMP throws
`Warning: Undefined array key "admin-bar" in XXX/wp-content/plugins/amp/includes/class-amp-theme-support.php on line 1382`
I removed the styles (and the whole admin bar) with
```
add_filter( 'show_admin_bar', '__return_false' );
wp_deregister_style( 'admin-bar' );
```
If I take out `wp_deregister_style( 'admin-bar' );` it works again.

### Expected Behaviour

Should not throw warning

### Screenshots

_No response_

### PHP Version

8.2

### Plugin Version

2.5.3

### AMP plugin template mode

Standard

### WordPress Version

_No response_

### Site Health

_No response_

### Gutenberg Version

_No response_

### OS(s) Affected

_No response_

### Browser(s) Affected

_No response_

### Device(s) Affected

_No response_

### Acceptance Criteria

_No response_

### Implementation Brief

on line 1382 includes/class-amp-theme-support.php you should replace
`is_array( wp_styles()->registered['admin-bar']->deps ) && in_array( $handle, wp_styles()->registered['admin-bar']->deps, true ) ? [..]
`
by
`isset( wp_styles()->registered['admin-bar']->deps ) && is_array( wp_styles()->registered['admin-bar']->deps ) && in_array( $handle, wp_styles()->registered['admin-bar']->deps, true ) ? [..]`
(add an isset())

### QA Testing Instructions

_No response_

### Demo

_No response_

### Changelog Entry

_No response_

Start in includes/class-amp-theme-support.php around line 1382, where the admin-bar dependency is accessed. Guard that dependency lookup when the admin-bar style has been deregistered, then verify that an AMP page with the provided WordPress filters no longer emits the undefined-array-key warning.

Written by the indexing model from the issue text.