Fix vulnerabilities; Add CI workflow

[DeveloperRic]

• Fixes high & low vulnerabilities in installed packages
• Adds a CI workflow to automatically run testonly & posttest scripts on push to master or on PR
  • I made the test stage run npm run testonly && npm run posttest because npm test includes a call to the integration script which is broken :(
• Would also be helpful to protect the master branch & make all jobs in the CI workflow required for PRs