Update gluon Docker tag to v0.5.15

This MR contains the following updates:

Package	Update	Change
gluon	patch	0.5.14 -> 0.5.15

Complete MR checklist

Assignee

• Followed upgrade instructions outlined in docs/DEVELOPMENT_MAINTENANCE.md
• Update Docs with new/updated steps as needed
• Tested and Validated Changes made with supporting info like logs or screenshots from test pipelines

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• Tested and Validated changes

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Upgrade Notices

From Chart versions < 1.19.0

N/A