macos seems to be in a failing mode. so let's investigate.

[KevinRansom]

Okay this failed for a couple of different reasons.

1. #r "nuget : executes in a different location from the tests and so had additional unintentional sources specified. So job 1 was to disable that. This was done by generating a Nuget.config alongside the packagemanagement project with inherited sources cleared.
2. One of the failing tests, wasn't testing anything useful. TBH ... wasn't doing what I believe the test author was trying to achieve. For this one I cleaned up the test a bit, and disabled with a new issue the dodgiest part of the test. It will need product work to do what was intended.
3. Now that we are no longer relying on reaching nuget.org via a kind of back door, We had to add FSharp.Data, 3.3.3 to the dotnet-public mirror.