dockerfile: update to Debian 12 #347

Job	Run time
Build, stable, linux/arm64	1h 42m 51s
Build, stable, linux/amd64	12m 37s
Test basic, stable, linux/amd64	2m 45s
Test novolume, stable, linux/amd64	3m 25s
Test, stable, linux/amd64	2h 11m 1s
Anchore Container Scan, linux/amd64	1m 56s
Test SAML, stable, linux/amd64	3m 5s
Test split, stable, linux/amd64	3m 47s
Test SSL, stable, linux/amd64	3m 27s
Trivy Container Scan, linux/amd64	3m 36s
Publish to GitHub, stable	0s
Publish to Docker Hub, stable	0s
	4h 28m 30s

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