Fix tasks JSON format

[davidchesnut]

Thank you for your pull request! Please provide the following information.

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Change Description:

Fixes incorrect formatting in the tasks.json file.

1. Do these changes impact any npm scripts commands (in package.json)? (e.g., running 'npm run start') If Yes, briefly describe what is impacted. No.

2. Do these changes impact VS Code debugging options (launch.json)? If Yes, briefly describe what is impacted. tasks.json

3. Do these changes impact template output? (e.g., add/remove file, update file location, update file contents) If Yes, briefly describe what is impacted. tasks.json

4. Do these changes impact documentation? (e.g., a tutorial on https://docs.microsoft.com/en-us/office/dev/add-ins/overview/office-add-ins) If Yes, briefly describe what is impacted. No

If you answered yes to any of these please do the following:

Include 'Rick-Kirkham' in the review Make sure the README file is correct

Validation/testing performed:

Describe manual testing done.