Release 1.0.1

[chriswilty]

Planned patch release for v1.0, in which we upgrade all package dependencies to latest stable version, though avoiding major version bumps where not possible due to code or package conflicts.

npm audit declares no remaining package vulnerabilities (at the current time).

Note that langchain lib was upgraded to latest 0.1.* version, which not only introduces package structure changes, but also deprecates or discourages certain old-style constructs. Those are not tackled here, instead they will be addressed in #898