ci: enable automated compile of the PDF (easier to collaborate)

.github/workflows/build.yml

@@ -0,0 +1,56 @@
+name: Build PDF
+
+env:
+    REGISTRY: ghcr.io
+
+jobs:
+
+    set-vars:
+        runs-on: [ubuntu-latest]
+        outputs:
+            CI_IMAGE : ${{ steps.common.outputs.CI_IMAGE }}
+        steps:
+            - name: Export common variables.
+              id  : common
+              run : |
+                  echo "CI_IMAGE=${{ env.REGISTRY }}/${{ github.repository }}/latex" >> $GITHUB_OUTPUT
+
+    build-image:
+        needs: [set-vars]
+        runs-on: [ubuntu-latest]
+        container:
+            image: docker:latest
+        permissions:
+            packages: write
+        steps:
+            - uses: actions/checkout@v4
+
+            - uses: docker/setup-buildx-action@v3
+
+            - uses: docker/login-action@v3
+              with:
+                  registry: ${{ env.REGISTRY }}
+                  username: ${{ github.actor }}
+                  password: ${{ secrets.GITHUB_TOKEN }}
+
+            - uses: docker/build-push-action@v5
+              with:
+                  context: .
+                  platforms: linux-amd64
+                  push: true
+                  file: dockerfile
+                  tags: ${{ needs.set-vars.outputs.CI_IMAGE }}
+                  cache-from: type=registry,ref=${{ needs.set-vars.outputs.CI_IMAGE }}
+                  cache-to: type=inline
+                  labels: "org.opencontainers.image.source=${{ github.repositoryUrl }}"
+
+    build-pdf:
+        needs: [set-vars, build-image]
+        runs-on: [ubuntu-latest]
+        container:
+            image: ${{ needs.set-vars.outputs.CI_IMAGE }}
+        steps:
+            - uses: actions/checkout@v4
+
+            - run: |
+                make

dockerfile

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+FROM ubuntu:24.04
+
+RUN --mount=type=bind,source=requirements.txt,target=requirements.txt <<EOF
+
+    set -ex
+
+    apt update
+
+    apt --yes --no-install-recommends install $(grep -vE "^\s*#" requirements.txt  | tr "\n" " ")
+
+    rm -rf /var/lib/apt/lists/* 
+
+EOF

requirements.txt

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+texlive-latex-extra