Catodon 26.10.3 released: Update Node.js in Docker

Linked to https://codefloe.com/catodon/catodon/releases/tag/26.10.3

Release 26.10.3: 26.10.2 plus the Node releases of the October 2026 security advisory (advisory), and follow-ups from #663 that came after 26.10.2 was cut.

Update not necessary if you're on a bare metal installation - just make sure you have updated your Node.js to the October 21 security release - and have restarted Catodon afterwards.

​:catodon:​
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