build: delete scripts/release.ts

We used to use `scripts/release.ts` to update the monorepo.json, which
used to contain the current versions of all packages within the CLI
repo. However, since 08e91a9
we no longer keep track of versions in monorepo.json.

Currently, before each publish, a git tag is created and all packages
are versioned based off the latest tag.

Since we no longer use `release.ts` for publishing, this commit deletes
the file entirely.

The script could be used to print out the versions we are about to publish,
but this is already covered by `yarn admin packages --version`.
This is useful for the caretaker to confirm the version numbers prior to
publishing the packages.

Author: kyliau