Add Stateful API testing for Model Registry

[lugi0]

Description

This adds a test for stateful API testing of Model Registry. It also bumps Schemathesis to V4, which is still an alpha release but appears to work fine for this workload.
I will keep this as a draft until the openAPI spec is updated in the Model Registry repo to support Stateful testing, and we can then decide if we are ok with an alpha release being pulled or if we want to wait / downgrade to V3 (requires some rework due to breaking changes between the two major versions).
I have also added a new mark type, "fuzzer", which I'd use to indicate tests which are bound to fail due to their random nature.

How Has This Been Tested?

Multiple runs made from local with an updated openAPI spec file which have already identified some failures to address in Model Registry.

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[github-actions]

The following are automatically added/executed:

• PR size label.
• Run pre-commit
• Run tox

Available user actions:

• To mark a PR as WIP, add /wip in a comment. To remove it from the PR comment /wip cancel to the PR.
• To block merging of a PR, add /hold in a comment. To un-block merging of PR comment /hold cancel.
• To mark a PR as approved, add /lgtm in a comment. To remove, add /lgtm cancel.
  lgtm label removed on each new commit push.
• To mark PR as verified comment /verified to the PR, to un-verify comment /verified cancel to the PR.
  verified label removed on each new commit push.

Supported labels

{'/wip', '/lgtm', '/hold', '/verified'}

[lugi0]

On hold until kubeflow/model-registry#773 is merged

[lugi0]

/hold

[lugi0]

The test now works as we've updated the openAPI spec file in upstream, however I sometimes get a library error (hypothesis.errors.FlakyStrategyDefinition) I'm still trying to figure out. Opening the PR up for review but keeping it on hold until I get to the root case of the error

[lugi0]

/verified

[fege]

/lgtm

[github-actions]

Status of building tag latest: success.
Status of pushing tag latest to image registry: success.