TO-DROP: reduce to minimal reproducer

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

.github/workflows/main.yml

@@ -2,41 +2,13 @@ name: CI
 
 on: [push, pull_request]
 
-env:
-  DEVELOPER: 1
-
-# If more than one workflow run is triggered for the very same commit hash
-# (which happens when multiple branches pointing to the same commit), only
-# the first one is allowed to run, the second will be kept in the "queued"
-# state. This allows a successful completion of the first run to be reused
-# in the second run via the `skip-if-redundant` logic in the `config` job.
-#
-# The only caveat is that if a workflow run is triggered for the same commit
-# hash that another run is already being held, that latter run will be
-# canceled. For more details about the `concurrency` attribute, see:
-# https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#concurrency
-concurrency:
-  group: ${{ github.sha }}
-
 jobs:
-  dockerized:
-    name: ${{matrix.vector.jobname}} (${{matrix.vector.image}})
-    concurrency:
-      group: dockerized-${{ matrix.vector.jobname }}-${{ matrix.vector.image }}-${{ github.ref }}
-    strategy:
-      fail-fast: false
-      matrix:
-        vector:
-        - jobname: linux32
-          image: i386/ubuntu:focal
-          distro: ubuntu32-20.04
-    env:
-      jobname: ${{matrix.vector.jobname}}
-      distro: ${{matrix.vector.distro}}
+  demo:
+    name: demonstrate need for "deprecated" actions/upload-artifact in i386 containers
     runs-on: ubuntu-latest
-    container: ${{matrix.vector.image}}
+    container: i386/ubuntu:focal
     steps:
-    - name: Upload failed tests' directories
+    - name: Upload fails with 'exec /__e/node20/bin/node: no such file or directory'
       uses: actions/upload-artifact@v4
       with:
         name: some-artifact