Remove pyjwkest dependency from xblock-lti-consumer

[iamsobanjaved]

The usage of the pyjwkest library was removed and replaced with pyjwt in #349. However, the pyjwkest dependency itself was not removed in that PR.

This issue tracks the cleanup of that unused dependency. Please remove pyjwkest from the project and verify that there are no remaining imports or references to it in the codebase.

Tasks

• Remove pyjwkest from dependencies
• Search for and remove any leftover imports or usage
• Make sure CI is green and nothing is broken

[jristau1984]

This was previously attempted and ran into issues. Please work this locally and ensure there is ample review of any PRs before merging any changes. Note that there are several related tickets across different repos for this replacement.

[Faraz32123]

closing this issue in favor of #563