posh-jwt issues

X509Certificate2.PrivateKey is obsolete and does not provide data

According to [MS Docs for X509Certificate2.PrivateKey](https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.x509certificates.x509certificate2.privatekey?view=net-6.0) PrivateKey-Property is/becomes obsolete and therefore does not provide data anymore. Instead [RSACertificateExtensions.GetRSAPrivateKey](https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.x509certificates.rsacertificateextensions.getrsaprivatekey?view=net-6.0) should be used.

70B43r

README.md mistake or misinformation

Hi, according to your docs: > The module provides two main functions: New-Jwt, Test-Jwt (also aliased to Verify-JwtSignature), as well as service functions - **ConvertFrom-Base64UrlString**, **ConvertFrom-Base64UrlString**, Get-JwtHeader, and Get-JwtPayload. Descriptions...

francisco-lafe