fixup! release: build unsigned Ubuntu .deb package

We need to require a newer Ubuntu version because Git fails to build
with Ubuntu 16.04.

This is needed because Ubuntu 16.04 apparently has a horribly outdated
curl version and Git must at all cost drop support for it: 4c1b7e3
(Merge branch 'bc/drop-ancient-libcurl-and-perl', 2024-12-04). I just
wish that at times pragmatism would beat ideology, but it's not to be
had in this instance.

Unfortunately, it requires a bit more than just changing the Ubuntu
version, as the newer version would now ask interactively for the
timezone while setting up the `tzdata` package.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

.github/workflows/build-git-installers.yml

@@ -493,7 +493,7 @@ jobs:
   create-linux-unsigned-artifacts:
     runs-on: ubuntu-latest
     container:
-      image: ubuntu:16.04 # expanded security maintenance until 04/02/2026, according to https://endoflife.date/ubuntu
+      image: ubuntu:20.04 # security support until 04/02/2025, according to https://endoflife.date/ubuntu
       volumes:
         # override /__e/node20 because GitHub Actions uses a version that requires too-recent glibc, see "Install dependencies" below
         - /tmp:/__e/node20
@@ -502,6 +502,11 @@ jobs:
       - name: Install dependencies
         run: |
           set -ex
+
+          # Prevent the dialog that asks interactively for the timezone
+          export DEBIAN_FRONTEND=noninteractive
+          export TZ=Etc/UTC
+
           apt-get update -q
           apt-get install -y -q --no-install-recommends \
             build-essential \