fix: update version check for Airflow to use strict inequality

src/airflow_mcp_server/tools/tool_manager.py

@@ -56,7 +56,7 @@ async def get_airflow_tools(config: AirflowConfig, mode: str = "unsafe") -> list
         airflow_version = version_result.get("version")
         if airflow_version is None:
             raise RuntimeError("Could not determine Airflow version from get_version tool.")
-        if parse_version(airflow_version) <= parse_version("3.1.0"):
+        if parse_version(airflow_version) < parse_version("3.1.0"):
             raise RuntimeError(f"Airflow version {airflow_version} is not supported. Requires >= 3.1.0.")
 
     tools = []