Exception: Could not create SSL/TLS secure channel

[dracan]

I've started getting the following exception ...

System.AggregateException: One or more errors occurred. ---> System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel.
   at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   at System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar)

I'm guessing it's related to this:
https://developer.github.com/changes/2018-02-01-weak-crypto-removal-notice/

A related issue discussing workarounds (eg. updating to .NET 4.6 or using ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;) can be found here:
octokit/octokit.net#1756

I've mentioned this to @gep13, and he said he knows the issue from other projects, so will take a look.