Upgraded to latest version of module serialize-to-js

[z3dev]

The serialize-to-js module was missing from the dependencies, which is required as part of the web flow functionality. As such, the require also had to change, as the module has recently gone through some API changes.

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[kaosat-dev]

Good catch !
There is only one potential issue with that version: they removed the 'deserialize' function from the package, which we need in order to unpack the data (for now disabled, since it is tied to VTree changes...sigh). Will merge this.