Bump ezid-client from 1.8.0 to 1.9.1

Bumps ezid-client from 1.8.0 to 1.9.1.

Release notes

Sourced from ezid-client's releases.

v1.9.0

• Migrates CI from Travis to GitHub actions.
• Adds code to catch unexpected HTML responses and to retry server error and unexpected response error 2 times before re-raising.

Commits

• 977813b Merge pull request #91 from duke-libraries/retry-bug
• cb631b7 Run GitHub workflows on main
• 802e92e Version 1.9.1
• 24cc925 Merge branch 'release-1.9.0' into main
• 4220c1e Version 1.9.0
• 5ac228e Release 1.9.0.rc1
• df22305 Fix tests and CI
• 20e3bc4 Update request.rb
• 943547d Delete .travis.yml
• e9e20cb Update ruby.yml
• Additional commits viewable in compare view