fix: add pragma no branch for coverage on reconnection error path

The isinstance check for JSONRPCRequest always evaluates to True
because _handle_reconnection is only called for request messages.
Mark the branch with pragma: no branch to satisfy 100% branch coverage.

Author: Andrey Barchenkov

src/mcp/client/streamable_http.py

@@ -382,7 +382,7 @@ async def _handle_reconnection(
         # Bail if max retries exceeded
         if attempt >= MAX_RECONNECTION_ATTEMPTS:
             logger.warning(f"Max reconnection attempts ({MAX_RECONNECTION_ATTEMPTS}) exceeded")
-            if isinstance(ctx.session_message.message, JSONRPCRequest):
+            if isinstance(ctx.session_message.message, JSONRPCRequest):  # pragma: no branch
                 error_data = ErrorData(
                     code=INTERNAL_ERROR,
                     message=f"SSE stream disconnected after {MAX_RECONNECTION_ATTEMPTS} reconnection attempts",