retry git command that time out once

Here is an error I want to see less of. One context in which this error comes up often is running test-get-vihi-annotations while connected to VPN so this might be a way to test. Another option is to set the timeout to some ridiculously small amount of time.

> Error in `run_git_command(repo, "fetch --tags --prune --prune-tags")`: Error executing git command:
>
> fetch --tags --prune --prune-tags
>
> Error message:
>
> fatal: unable to access 'https://github.com/bergelsonlab/vihi_annotations.git/': Failed to connect to github.com port 443 after 21057 ms: Couldn't connect to server
>