* [python] Cleanup ThreadPool with atexit rather than __del__
This removes the `__del__` function from the generated Python client,
and replaces it with a `cleanup` function. When a ThreadPool is created,
the cleanup function is registered with the `atexit` module.
This fixes#5093, where the API client could hang indefinitely at
garbage collection.
* Update petstore examples
* Test to ensure threadpool is cleaned up
* Docs now encourage using the context manager
* Regenerate docs
* Update samples
* Adds composed model support for allOf oneOf anyOf
* Moves discriminator into discriminator() class method, adds test_deserialize_lizard, adds setting discriminator using allOf schema
* add test cases to cover different collection format
* add space params to retrofit 1.x
* add space params to retrofit 2.x
* rename url to localVarUrl
* fix exception in haskell servant
* Adds v2 spec additionalproperties examples, adds v3 spec nulllable model example, updates samples
* Remaining samples updates
* Adds csharp generator update to handle models with multilevel parent types, which works for the AdditionalPropertiesObject model, samples updated
* Issue 1766 Modified mustache files for Go to support nullable in the spec v3.0+; Updated model files running .sh scripts for Go.
* Add "nullable" to fake yaml
* Add sample script for OAS3
* Fix output folder (openapi3)
* Run bin/openapi3/go-petstore.sh
* Update samples
* Update jaxrs-jersey
* Update python and php samples
* Add bin/openapi3/go-gin-petstore-server.sh
* Run bin/openapi3/go-gin-petstore-server.sh
* Update bin/openapi3/go-petstore-server.sh to generate "nullable" samples
* Run bin/openapi3/go-petstore-server.sh
* Fix duplicated `import`
* add multiple server support to python client
* various fixes
* minor fixes, add tests
* test oas2 python first
* fix tests
* fix issues reported by flake8
* update code format
* add python petstore to ensure up-to-date
* rearrange test
* fix E501
* fix tests
* add new files
* fix script permission
* fix index check
* update samples
