u64 input parameters to Node Service is deserialized to float

[kikakkz]

Description
We add an api here https://github.com/respeer-ai/linera-protocol/blob/1049478889b0c7ff7ba1a2c02075465a2a0eb505/linera-service/src/node_service.rs#L906 to let CheCko submit ExecutedBlock with its signature. But the ExecutedBlock cannot be deserialized correctly.

Screenshots

**From @afck **
https://discord.com/channels/984941796272521226/1098657437965365289/1301122278268076052 I think we'll need to serialize all integers greater than u32 as strings