refactor: 💡 refactor

[mkercheval-tva]

• Upgraded to .NET 8

• Removed dependencies on RestSharp and Newtonsoft

• Replaced Newtonsoft with System.Text.Json for serialization

• Addressed issue of incompatible use of System.Text.Json and Newtonsoft

• Modernized TaxjarAPI with the following objectives:

  • Made implementation injectable and testable
  • Utilized HttpClientFactory for best practices
  • Minimized reflection usage

• Created public ITaxjarApi interface for custom implementations and mocks

• Changed date properties from string to DateTime for proper serialization and direct access

• Created TaxjarApiOptions class for configurable options

• Added AddTaxjar extension method to register Taxjar with the service collection

• Replaced RestSharp with HttpClientFactory to prevent port exhaustion and outdated DNS, and to leverage Polly for resilience

• Removed all synchronous methods to embrace asynchronous operations in HttpClient

• Changed method signatures to use strongly typed records instead of anonymous objects

• Removed calls to GetProperty() and GetValue()

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[boylec]

this refactor is great - I hope it gets merged.