[Internal] Update SDK to latest OpenAPI spec (#766)

## Changes
<!-- Summary of your changes that are easy to understand -->
Updating SDK to latest OpenAPI spec + fix generation (need to import
`Optional`)

Note: `test_github_oidc_flow_works_with_azure` fails on genkit
generate-sdk py but passes when run separately right after generation
without any change. This seems to be non blocker so going ahead with SDK
generation.

## Tests
<!-- 
How is this tested? Please see the checklist below and also describe any
other relevant tests
-->
Unit tests. Nightly tests will run over release PR.
- [ ] `make test` run locally
- [ ] `make fmt` applied
- [ ] relevant integration tests applied

.codegen/__init__.py.tmpl

@@ -9,6 +9,7 @@ from databricks.sdk.mixins.workspace import WorkspaceExt
 from databricks.sdk.service.{{.Package.Name}} import {{.PascalName}}API{{end}}
 from databricks.sdk.service.provisioning import Workspace
 from databricks.sdk import azure
+from typing import Optional
 
 {{$args := list "host" "account_id" "username" "password" "client_id" "client_secret"
   "token" "profile" "config_file" "azure_workspace_resource_id" "azure_client_secret"

.codegen/_openapi_sha

@@ -1 +1 @@
-d05898328669a3f8ab0c2ecee37db2673d3ea3f7
+248f4ad9668661da9d0bf4a7b0119a2d44fd1e75