dockerfile: update to Debian 12 #348

Job	Run time
Build, stable, linux/amd64	12m 35s
Build, stable, linux/arm64	2h 1m 57s
Test novolume, stable, linux/amd64	3m 32s
Test SAML, stable, linux/amd64	3m 12s
Test basic, stable, linux/amd64	4m 10s
Test, stable, linux/amd64	2h 6m 3s
Anchore Container Scan, linux/amd64	1m 56s
Test split, stable, linux/amd64	3m 30s
Test SSL, stable, linux/amd64	2m 50s
Trivy Container Scan, linux/amd64	2m 57s
Publish to Docker Hub, stable	0s
Publish to GitHub, stable	0s
	4h 42m 42s

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