test: add API version management tests

[jhamon]

Summary

Add comprehensive unit tests to verify the API version management infrastructure works correctly across all API categories.

Closes SDK-100

Background

After reviewing the codebase, the API version management infrastructure is already in place:

• Each generated module (db_control, db_data, inference, oauth, admin) has its own API_VERSION constant
• Client classes import their module-specific version
• setup_openapi_client() correctly sets the X-Pinecone-API-Version header

This PR adds tests to verify this infrastructure continues to work correctly.

Test Coverage

The new tests verify:

1. Module API versions - Each generated module has the correct version:

   • db_control, db_data → 2026-01.alpha (for FTS support)
   • inference, oauth, admin → 2025-10 (stable)

2. Header setting - setup_openapi_client() correctly sets/omits the version header

3. Client imports - Index, Inference, and Admin classes import the correct API versions

4. gRPC compatibility - gRPC uses the shared API_VERSION from openapi_support

Test Results

tests/unit/utils/test_api_version_management.py - 12 passed
tests/unit/utils/test_setup_openapi_client.py - 4 passed

---

Note

Low Risk
Low risk: adds unit tests only, but they hard-code version strings and could become brittle when API versions roll.

Overview
Adds a new unit test suite (tests/unit/utils/test_api_version_management.py) to enforce API version selection across SDK surfaces.

The tests assert each generated OpenAPI module exposes the expected API_VERSION (alpha for db_control/db_data, stable for inference/oauth/admin), verify setup_openapi_client() sets/omits the X-Pinecone-API-Version header based on the api_version argument, and confirm key wrappers (Index/Inference/Admin) plus the shared gRPC openapi_support.api_version.API_VERSION reference the expected version.

^{Written by Cursor Bugbot for commit 3983f3c. This will update automatically on new commits. Configure here.}