[ENGINE-8673]: Adding estimated import charges in shipments (#121)

Autogenerate the SDK from the OpenAPI spec (3.0.0) (#102)

* Use nullable reference types and datetimeoffset

* Mark non-required types as nullable

* Add required keyword to required properties

* Mark API method parameters as optional

* Allow SDK to handle No Content (204) responses

Previously, the SDK would throw an exception when trying to parse an empty string.
Now we will return the empty string, if a string response is requested.

If the caller was expecting a deserialized type, an exception will still be raised for no content.

* Remove version from generated files

Including the version in every file causes every file to be modified
any time the generator is run. This creates a large diff that obscures the actual changes.
The version is already known in the generation/swagger.json file.

Add warning that file is generated and should not be modified.

* Verify can deserialize create label response

Convert doubles to decimals

* Add optional error properties

Allow arbitrary values in advanced_options.

* added A4 and A6 to label layout enum

* Mark v2 methods as obsolete

* Add generated documentation

* Update supported .NET versions

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Co-authored-by: Joshua Flanagan <joshuaflanagan@gmail.com>
Co-authored-by: Matt Burton <matt.burton@gmail.com>
Co-authored-by: Joe Pill <joe.pill@auctane.com>
Co-authored-by: Bibhusan-Shah <bibhusan.shah@auctane.com>
Co-authored-by: Bibhusan-Shah <87672403+Bibhusan-Shah@users.noreply.github.com>

Support code TrackingStatusCode.SP #118 #118 (#120)

Merge pull request #107 from ShipEngine/ENGINE-7190-funding-sources-w…

…allet-errors

Added error codes for funding sources errors

Merge pull request #117 from ShipEngine/jpill/update-error-enum

feat: add MultipackageNotSupported error

Merge pull request #116 from ShipEngine/bshah/adding-label-layouts

added A4 and A6 to label layout enum

Update version

Merge pull request #114 from ShipEngine/jpill/update-system-text-json

chore: update System.Text.Json to latest

Add optional error properties

Regenerate from spec v1.20.5, version 3.0.0-beta.13