chore: overhaul releasing workflow, supported frameworks

[Justintime50]

Description

• Copies the recent releasing workflow changes from the C# lib to this package verbatim (only changing EasyPost to EasyVCR).
• Updates the supported C# frameworks to match the C# lib for easier maintenance (the other frameworks dropped are also very deprecated
• Like the C# lib, switches actually testing this package on .NET Standard (not possible on Applie Silicon) to doing a compile test only on CI. Gets us the ultimate same results while unlocking the ability to test this package on Apple Silicon during local dev.

Testing

All CI tests pass.

Pull Request Type

Please select the option(s) that are relevant to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)

To fix this issue, we should add a permissions block specifying the minimal required permissions for all jobs. The CodeQL suggestion for a minimal starting point is contents: read. The best way to implement this is to add a permissions: section at the root level of the workflow, before the jobs: block. This will ensure all jobs inherit these limited permissions unless overridden at the job level. No other workflow functionality will be affected by limiting permissions to read-only, so this change is safe and applies across all jobs as a best practice.

Changes needed:

• Edit .github/workflows/ci.yml.
• Insert the following block after the workflow name (line 2 or 3), before the on: block:

  permissions:
    contents: read
  

• No additional imports, methods, or definitions are required; this is a declarative change in a YAML file.