fix: Set to Py27Dict if components is explicitly set to None (#3373)

Co-authored-by: Aayush thapa <[email protected]>

Author: GavinZZ

samtranslator/open_api/open_api.py

@@ -518,6 +518,10 @@ def openapi(self) -> Dict[str, Any]:
 
         if self.security_schemes:
             self._doc.setdefault("components", Py27Dict())
+            if not self._doc["components"]:
+                # explicitly set to dict to account for scenario where
+                # 'components' is explicitly set to None
+                self._doc["components"] = Py27Dict()
             self._doc["components"]["securitySchemes"] = self.security_schemes
 
         if self.info: