Provide methods for closing and create the httpx session in AsyncFire…

…crest

firecrest/AsyncClient.py

@@ -217,6 +217,17 @@ def set_api_version(self, api_version: str) -> None:
         """
         self._api_version = parse(api_version)
 
+    async def close_session(self) -> None:
+        """Close the httpx session"""
+        await self._session.aclose()
+
+    async def create_new_session(self) -> None:
+        """Create a new httpx session"""
+        if not self._session.is_closed:
+            await self._session.aclose()
+
+        self._session = httpx.AsyncClient()
+
     @_retry_requests  # type: ignore
     async def _get_request(
         self, endpoint, additional_headers=None, params=None