Remove prebuild.sh step

This script creates a file at `src/version.ts` which reflects the `version` value from `package.json` in the root. If one attempts to build the solution `npx tsc --outDir ./build/` without running it, one gets errors showing that the module doesn't exist because the file isn't saved in the repo and only generated as part of this step.

This is less than ideal and should be corrected.