fix pull request triggers for optional workflows

[zacharyburnett]

This PR addresses an issue where labeling a pull request does not trigger the devdeps workflow (see #210).

Added triggers to the workflows on @braingram 's suggestion: https://github.com/spacetelescope/stdatamodels/pull/211#discussion_r1330688085

Checklist

• [x] ~added entry in CHANGES.rst (either in Bug Fixes or Changes to API)~
• [x] ~updated relevant tests~
• [x] ~updated relevant documentation~
• [x] updated relevant milestone(s)
• [x] added relevant label(s)

[codecov[bot]]

Codecov Report

Patch has no changes to coverable lines.

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[zacharyburnett]

https://github.com/spacetelescope/stdatamodels/actions/runs/6248558561/workflow#L17

[zacharyburnett]

adding the triggers appears to have fixed the issue

[braingram]

Sorry I missed that the windows ones were running and appear to be failing: https://github.com/spacetelescope/stdatamodels/actions/runs/6248717397/job/16963920785