Add release notes for every release

[freddyaboulton]

• I have searched to see if a similar issue already exists.

Is your feature request related to a problem? Please describe.
As a gradio user, it is unclear to me what changes were made in between gradio releases.

Describe the solution you'd like
I would like to see release notes for every release on github and or the gradio.app website so I can determine if I should upgrade to a new version of gradio.

Additional context
Related to #1646

[abidlabs]

cc @aliabd

[freddyaboulton]

@pngwn I recall you said something about not liking automated release notes?

I haven't used them before, but I think Github's automated release notes feature could be a quick way to start providing more info to uses regarding changes.

And it seems to integrate nicely with the action we're using to create the github relesae. All it seems we have to do is start labelling our PRs with what kind of change they are.

Curious on your thoughts, or anyone else's!