Use a tool to bump the versions in files based on tag

[ericwb]

Is your feature request related to a problem? Please describe.
Once we start releasing versioned tags, we should take advantage of bumpversion to automatically update files with a version number in them. Currently package.json has a version, but more files have one in the future.

Describe the solution you'd like
Use bumpversion

Describe alternatives you've considered
n/a

Additional context
n/a

[evqna]

Are you specifically referencing the Python tool or any similar alternative?

[evqna]

Apparently the npm CLI has a command just for this: https://docs.npmjs.com/cli/version.html

[evqna]

Same with Yarn: https://yarnpkg.com/lang/en/docs/cli/version/

[ericwb]

Yep, since we only have a version in the package.json currently, might as well use the npm command.