Automate releases on tags

[EdricChan03]

Currently, I've been manually creating releases using GitHub's web interface and copying and pasting the release notes from release-notes.json. However, this can eventually be troublesome.

EDIT: Here's a checklist indicating the things to be done for the new tags workflow:

• Pull-in changes from release-notes.json
• Add support for retrieving updated/moved/added/removed dependencies in package.json
• Add support for including merged PRs in the release notes
• Remove draft mode (?) once stable

[EdricChan03]

This has been partially implemented in 7870914, however I've kept it in draft mode for now.

Here's an example template of a release's notes:

## Release notes

### Site release notes

(changes pulled in from `release-notes.json` in a bullet format)

## Internal changes

(blah blah)

### `package.json` changes

(changes that modify `package.json` here)

#### Dependency changes

##### Removed dependencies

(can omit this header and all descendants if no deps have been removed)

###### `dependencies`

Name | Commit | Notes
---|---|---
[`example-package`](https://npmjs.com/package/example-package) | (commit SHA) | (any notes, or a dash)

##### `devDependencies`

(same table from above)

(same section for "added" and "moved" deps)

[github-actions]

This issue will be closed in 7 days as it has been open for 30 days with no activity.
To prevent the issue from being closed, either comment on this issue or remove the "status: stale" label.