add Linux 5.15.131 packages

[cfm]

Status

Ready for review

Description of changes

Originally intended just to rebuild #202 with
freedomofpress/kernel-builder#38, this also moved us from v5.15.30 to v5.15.131.

Towards:

• September 2023 Linux kernel update securedrop#6938
• September 2023 Linux kernel update securedrop-workstation#916

Checklist

• CI passes.

• Manual verification confirms that Revert "Explicitly depend on linux-image-5.15.89-grsec-securedrop (temporarily)" kernel-builder#38 took effect, e.g.:

  user@sd-dev:~/securedrop-apt-test$ debdiff core/focal/securedrop-grsec_5.15.130-1-grsec-securedrop-1_amd64.deb core/focal/securedrop-grsec_5.15.131-1-grsec-securedrop-1_amd64.deb 
  File lists identical (after any substitutions)
  
  Control files: lines which differ (wdiff format)
  ------------------------------------------------
  Depends: [-linux-image-5.15.130-1-grsec-securedrop,-] {+linux-image-5.15.131-1-grsec-securedrop,+} intel-microcode, amd64-microcode, [-paxctld, linux-image-5.15.89-grsec-securedrop-] {+paxctld+}
  Version: [-5.15.130-1-grsec-securedrop-1-] {+5.15.131-1-grsec-securedrop-1+}

• Build logs have been committed to build-logs: freedomofpress/build-logs@c2137c0

[rocodes]

• CI passing / hashes match build logs
• Build logs committed

[cfm]

NB. 55e2cb7 contains a typo and should read:

 Originally intended just to rebuild https://github.com/freedomofpress/securedrop-apt-test/pull/202 with
-https://github.com/freedomofpress/kernel-builder/pull/38[1], this also moved us from v5.15.30 to
+https://github.com/freedomofpress/kernel-builder/pull/38[1], this also moved us from v5.15.130 to
 v5.15.131.

 Towards:
 - https://github.com/freedomofpress/securedrop/issues/6938
 - https://github.com/freedomofpress/securedrop-workstation/issues/916

 [1]: https://github.com/freedomofpress/securedrop/issues/6938#issuecomment-1709126141