GithubDataSource based importers failing due to rate limit #507

The github rate limiting docs say

For unauthenticated requests, the rate limit allows for up to 60 requests per hour. Unauthenticated requests are associated with the originating IP address, and not the user making requests.

We're getting aiohttp.client_exceptions.ClientResponseError: 429, message='Too Many Requests'. Perhaps

• Using github by api and using secret tokens or
• Using subversion to fetch tags
  Could help us