Add C# request signature example

[alexheretic]

#51 for C#

C# request signature example

Sends a signed request to https://api.truelayer-sandbox.com/test-signature.

Run

Set environment variables:

• ACCESS_TOKEN A valid JWT access token for payments scope docs.
• KID The certificate/key UUID for associated with your public key uploaded to console.truelayer.com.
• PRIVATE_KEY Private key PEM string that matches the KID & uploaded public key.
  Should have the same format as this example private key.

$ dotnet run
Sending ...

204 ✓

[alexheretic]

For some reason github actions are only running java tests 😞