[Snyk] Security upgrade debian from bookworm-20240701 to 12.9

[cmars]

Snyk has created this PR to fix 5 vulnerabilities in the dockerfile dependencies of this project.

Keeping your Docker base image up-to-date means you’ll benefit from security fixes in the latest version of your chosen image.

Snyk changed the following file(s):

• build/Dockerfile

We recommend upgrading to debian:12.9, as this image has only 35 known vulnerabilities. To do this, merge this pull request, then verify your application still works as expected.

Vulnerabilities that will be fixed with an upgrade:

	Issue	Score
	Algorithmic Complexity SNYK-DEBIAN12-GNUTLS28-8705121	586
	Algorithmic Complexity SNYK-DEBIAN12-LIBTASN16-8689970	586
	Integer Overflow or Wraparound SNYK-DEBIAN12-ZLIB-6008963	500
	CVE-2025-1390 SNYK-DEBIAN12-LIBCAP2-8732577	221
	Information Exposure SNYK-DEBIAN12-GLIBC-1546991	150

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[!IMPORTANT]

• Check the changes in this PR to ensure they won't cause issues with your project.
• Max score is 1000. Note that the real score may have changed since the PR was raised.
• This PR was automatically created by Snyk using the credentials of a real user.

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