fix: reject JSON-RPC requests with id: null instead of misclassifying as notification#2168

giulio-leone wants to merge 4 commits intomodelcontextprotocol:mainmodelcontextprotocol/python-sdk:mainfrom

giulio-leone:fix/jsonrpc-null-id-validationgiulio-leone/python-sdk:fix/jsonrpc-null-id-validationCopy head branch name to clipboard