patchdemo: Upgrade Composer to 2.9.6

Brennen Bearnesrequested to merge
work/patchdemo-composer into main

For the main patchdemo image, this installs composer directly rather than using apt. Just adds changelog entries for the Catalyst images that didn't get caught in my earlier rebuild of the bookworm stuff.

cc: @jhuneidi @jnuche

Bug: T410453

Edited by Brennen Bearnes

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