CI: Update for gdal requirement

[maxrjones]

Description of proposed changes

Follow-up to #6258, update CI workflows for gdal being a required dependency.

Fixes #

Reminders

• Make sure that your code follows our style. Use the other functions/files as a basis.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Describe changes to function behavior and arguments in a comment below the function declaration.
• If adding new functionality, add a detailed description to the documentation and/or an example.

[seisman]

Also need to update the branch protection rules.

[maxrjones]

Also need to update the branch protection rules.

I'll update after the branch is ready/approved so it doesn't interfere with other PRs.