adapt test for 0.10.x and reproduce race conditions with HTTP

[mborne]

This pull request introduces several important changes to improve test reliability and support for the upcoming geocontext version. The main enhancements are the addition of a test to catch concurrent tool call response crossing, improved session management in test fixtures to avoid this issue, and conditional test/tool logic to support both the current and future versions of geocontext. Additionally, test execution is now explicitly set to run sequentially to prevent session-related bugs.

Test reliability and concurrency handling: (refs #33)

• Added test_mcp_concurrency.py, a test that verifies concurrent tool calls to geocontext do not cross their responses, addressing a known issue with HTTP transport in version 0.10.x.
• Refactored the mcp_tools fixture in conftest.py to ensure only one MCP session per server is used throughout the test session, preventing response crossing during concurrent tool calls.

Version compatibility and conditional logic: (refs #27)

• Updated config/constants.py to define new tool names and conditionally include them in EXPECTED_TOOLS when GEOCONTEXT_DEV is enabled, supporting both legacy and upcoming tool naming conventions. [1] [2]
• Modified test files to use TOOL_GPF_COUNT_FEATURES instead of TOOL_GPF_GET_FEATURES when GEOCONTEXT_DEV is enabled, ensuring tests pass with both versions. [1] [2] [3]

Test execution configuration: (refs #33)

• Updated pyproject.toml to force pytest to run tests sequentially and disable xdist, ensuring a single MCP session is shared and avoiding concurrency issues with geocontext HTTP transport.