Allow Home Assistant to be updated by dependabot

[YorkshireIoT]

Checklist

• I have filled out the template to the best of my ability.
• This only contains 1 feature request (if you have multiple feature requests, open one feature request for each feature request).
• This issue is not a duplicate feature request of previous feature requests.

Is your feature request related to a problem? Please describe.

I'd like to automate the bumping of the HA version in requirements.txt

Describe the solution you'd like

Use dependabot to do this

Describe alternatives you've considered

N/A

Additional context

N/A