Running "dotnet restore" fails intermittently due to expired signature

### Description

I have been having an intermittent issue for a few months with `dotnet restore`. It will occasionally fail because:

> The repository primary signature's timestamping certificate is not trusted by the trust provider.

One of the packages that trigger this issue is `runtime.ubuntu.14.04-x64.runtime.native.System.Security.Cryptography.OpenSsl 4.3.0` and its certificate expired on "14/04/2021 14:00:00".

These packages are included because I'm using `XUnit.Assert 2.4.2`, which targets `netstandard1.1`, which includes `System.Net.Http 4.3.0`.

[I've made a very simple project that replicates this issue.](https://github.com/julian94/RestoreProblemReproduction)

The troubling thing with this issue is that it's intermittent, it will only trigger on the first fetch of a package from nuget. Running `dotnet restore` again after a failed attempt will succeed. This can be used as a workaround, but indicates that package signatures are only verified when downloaded, and then trusted afterwards.

### Configuration
Reproduced using DotNet SDK `6.0.307` & `7.0.102`.
Using Windows Server 2022 Standard with all windows updates applied.

### Regression?

### Other information
[Here's a full diagnostic log of dotnet restore.](https://pastebin.com/FKQAkMRN)

A simple workaround is to run `dotnet restore` again if it fails the first time.