[PATCH] ci: bump debian-11 job to debian-12

[Jeff King <peff@peff.net>]

Debian 11 just recently went out of its LTS period, and is unmaintained
by the project (there is "Extended LTS", but it is a paid service
provided by a third party).

The point of the debian-11 job was to cover older releases in the LTS
state, per ac112fd4f0 (Add additional CI jobs to avoid accidental
breakage, 2024-10-31). Bumping to debian-12 will cover us there for the
next 2 years.

Signed-off-by: Jeff King <peff@peff.net>
---
I started looking at this because I got an apt failure on a debian-11
job today. It might have just been a transient mirror failure (although
it reproduced for several minutes afterwards). But this seems like the
right step forward anyway.

I tested the GitHub job, but not the GitLab one. They should be pulling
the same docker images, though, so I would expect it to Just Work.

 .github/workflows/main.yml | 6 +++---
 .gitlab-ci.yml             | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 205325eb33..a0c3f53c6d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -411,9 +411,9 @@ jobs:
         # A RHEL 8 compatible distro.  Supported until 2029-05-31.
         - jobname: almalinux-8
           image: almalinux:8
-        # Supported until 2026-08-31.
-        - jobname: debian-11
-          image: debian:11
+        # Supported until 2028-06-30.
+        - jobname: debian-12
+          image: debian:12
     env:
       jobname: ${{matrix.vector.jobname}}
       CC: ${{matrix.vector.cc}}
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0242283c3c..cd6fd4a504 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -71,9 +71,9 @@ test:linux:
       # A RHEL 8 compatible distro.  Supported until 2029-05-31.
       - jobname: almalinux-8
         image: almalinux:8
-      # Supported until 2026-08-31.
-      - jobname: debian-11
-        image: debian:11
+      # Supported until 2028-06-30.
+      - jobname: debian-12
+        image: debian:12
   artifacts:
     paths:
       - t/failed-test-artifacts
-- 
2.55.0.1127.g25100ff258