Update ubuntu Docker tag to v26

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
ubuntu	container	major	noble → resolute

---

Configuration

📅 Schedule: (in timezone America/New_York)

• Branch creation
  • At any time (no schedule defined)
• Automerge
  • At any time (no schedule defined)

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.

---

This change is 

[jwnimmer-tri]

+a:@tyler-yankee we probably don't want any of this? But I'll let you decide.

[tyler-yankee]

My understanding was that DEE uses Drake's primary platform / Ubuntu version for CI, so Noble for a while longer. If that changes, feel free to reopen the PR and we can discuss.

(Although, is there a particular reason we fatal error in the setup scripts when the user is not exactly Noble? They should work on newer/older Ubuntu, probably.)

[renovate]

Renovate Ignore Notification

Because you closed this PR without merging, Renovate will ignore this update. You will not get PRs for any future 26.x releases. But if you manually upgrade to 26.x then Renovate will re-enable minor and patch updates automatically.

If you accidentally closed this PR, or if you changed your mind: rename this PR to get a fresh replacement PR.