Drop faraday_middleware, allow Faraday 2.x (1.1.1)

[RichardVickerstaff]

Summary

faraday_middleware is deprecated upstream and will never ship a Faraday 2 compatible release. It was only pulled in here for :gzip — :json (request and response) and :raise_error are already core Faraday middleware, no gem needed for those.

• Replaces :gzip with the faraday-gzip gem, pinned to ~> 2.0 (which supports faraday >= 1.0).
• Relaxes faraday itself from ~> 1 to >= 1, < 3.

Test plan

• Full spec suite + standardrb against Faraday 1.10.6 (default resolution): 34 examples, 0 failures, clean lint.
• Ran bundle update faraday to force resolution to Faraday 2.14.3, reran both: 34 examples, 0 failures, clean lint.
• Confirmed faraday_middleware no longer appears in bundle list.

dealers_site depends on this gem directly and was one of the named hard blockers on the ecosystem Faraday 1→2 migration (Kanbanize card #121677, split from #75150) — this removes it.

🤖 Generated with Claude Code

[RichardVickerstaff]

The CircleCI failure here is a pre-existing infra issue, unrelated to this change: it fails at the git checkout step with git@github.com: Permission denied (publickey), before any code runs.

Confirmed this predates the PR:

• CircleCI's own pipeline API shows no completed pipeline has ever run on main for this repo.
• GitHub's commit status API shows CircleCI as permanently pending on main, with only unrelated Dependabot check failures in the recent history.

This means the project's CircleCI checkout SSH key/GitHub App integration needs to be re-added by someone with CircleCI project-admin access — it would fail on any commit right now, not just this one. Locally, the full spec suite + standardrb pass cleanly against both Faraday 1.10.6 and 2.14.3 (see PR description).