This PR update the tests suite to wait for Vercel CLI tarball and then use that tarball to run E2E tests.
This is valuable because it will package all the packages in this monorepo to make the tests follow more closely what will happen in production once merged.
Since the current "Find Changes" step takes about 2 minutes, we run that first (it happens concurrently with the tarball preparation). Then once we complete "Find Changes" we wait for the tarball but it will likely be ready by that point since it also takes about 2 minutes. After both of those steps, the E2E tests continue as usual but with the `VERCEL_CLI_VERSION` set to the tarball.
- Related to #7967
- Closes#8245
- Closes#8227
This PR does a few things:
- Changes the existing warning message for Python 3.6 to print a discontinue date
- Will automatically fail new Python 3.6 deployments created after that date
- Consolidates logic to make Python version selection work in a similar manner to Node.js version selection
- Changes tests from JS to TS