feat: Add support for shutdown method (#3)

Author: keelerm84

ld_openfeature/provider.py

@@ -19,6 +19,9 @@ def __init__(self, client: LDClient):
         self.__context_converter = EvaluationContextConverter()
         self.__details_converter = ResolutionDetailsConverter()
 
+    def shutdown(self):
+        self.__client.close()
+
     def get_metadata(self) -> Metadata:
         return Metadata("launchdarkly-openfeature-server")