.github/dependabot.yml: group @ngtools/webpack with Angular

[alanorth]

Description

@ngtools/webpack is provided by the Angular team and follows the same versioning so we should group it with Angular in dependabot.

See: https://github.com/angular/angular-cli

Instructions for Reviewers

Please add a more detailed description of the changes made by your PR. At a minimum, providing a bulleted list of changes in your PR is helpful to reviewers.

List of changes in this PR:

• Add @ngtools/webpack to the Angular group managed by dependabot

Include guidance for how to test or review your PR. This may include: steps to reproduce a bug, screenshots or description of a new feature, or reasons behind specific changes.

Checklist

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However, reviewers may request that you complete any actions in this list if you have not done so. If you are unsure about an item in the checklist, don't hesitate to ask. We're here to help!

• My PR is created against the main branch of code (unless it is a backport or is fixing an issue specific to an older branch).
• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using npm run lint
• My PR doesn't introduce circular dependencies (verified via npm run check-circ-deps)
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• If my PR fixes an issue ticket, I've linked them together.

[tdonohue]

👍 Thanks @alanorth ! This makes sense to me to group webpack with the Angular dependencies. Apologies it's taken so long for me to get back to this!