Dynamically update Predict On combo based on pipeline type

[roomrys]

Description

This is 1 of 2 or 3 expected PRs to fix re-tracking in SLEAP. This PR limits the GUI options for frames to "Predict On" to only sequential frames (when re-tracking is selected, i.e. Pipeline Type is "none").

Types of changes

• Bugfix
• New feature
• Refactor / Code style update (no logical changes)
• Build / CI changes
• Documentation Update
• Other (explain)

Does this address any currently open issues?

• FileNotFoundError when running inference, seems to be from saving project #1287

Outside contributors checklist

• Review the guidelines for contributing to this repository
• Read and sign the CLA and add yourself to the authors list
• Make sure you are making a pull request against the develop branch (not main). Also you should start your branch off develop
• Add tests that prove your fix is effective or that your feature works
• Add necessary documentation (if appropriate)

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