Add homebrew download stats

[kdheepak]

📋 Description

• Which service is this badge for: Homebrew
• What sort of information should this badge show?: Download stats
  Provide an example in plain text e.g: "downloads | 1200/year"

🔗 Data

Where can we get the data from?

• Is there a public API?: yes
• Does the API requires an API key?: No
• Link to the API documentation: https://formulae.brew.sh/formula/

🎤 Motivation

Please explain why this feature should be implemented and how it would be used.

• What is the specific use case?

It would be nice to show download stats from homebrew, similar to how we can now show download stats from github releases.

[calebcartwright]

I'm having a bit of deja vu with this request, though can't seem to find any issues where we've discussed it previously.

We wouldn't want to use https://formulae.brew.sh/api/formula.json as that's way too big and takes way too long to retrieve, but i guess we could look at the analytics.install fields in the formula-specific api response (which is what we use for the version badges) to get the raw data.

This would be a relatively easy badge to add, and would recommend anyone interested in implementing take a look at our tutorial as well as the existing homebrew version badge code for reference. Note it might be beneficial to extract the common bits out (like the fetch function) into a separate helpers file or a base class that the existing version badge and future downloads badge could extend

[kdheepak]

Thanks for the comment! I submitted a PR for this.