CI: remove linux-pdf for now.

I don't know what is going on with lmodern and lualatex.

.github/workflows/ci.yml

@@ -125,63 +125,6 @@ jobs:
           ! grep -q ": *[Ww]arning:" build.log || exit 1
           cabal ${{ matrix.versions.prefix }}test ${{ matrix.versions.cabalopts }} --disable-optimization ${{ matrix.versions.testopts }}
 
-  linux-pdf:
-
-    runs-on: ubuntu-18.04
-    strategy:
-      fail-fast: false
-      matrix:
-        pdfengine:
-          - xelatex
-          - lualatex
-          - pdflatex
-
-    steps:
-    - uses: actions/checkout@v2
-
-    - name: Install recent cabal/ghc
-      uses: haskell/actions/setup@v1
-      with:
-        ghc-version: 8.10.4
-        cabal-version: 3.2
-
-    # needed by memory
-    - name: Install numa
-      run: sudo apt-get install libnuma-dev
-
-    # needed to test pdf creation
-    - name: Install texlive
-      run: sudo apt-get install texlive-base texlive-latex-recommended texlive-xetex
-
-    # declare/restore cached things
-    # caching doesn't work for scheduled runs yet
-    # https://github.com/actions/cache/issues/63
-
-    - name: Cache cabal global package db
-      id:   cabal-global
-      uses: actions/cache@v2
-      with:
-        path: |
-          ~/.cabal
-        key: ${{ runner.os }}-8.10.4-3.2-cabal-global-${{ hashFiles('cabal.project') }}
-
-    - name: Cache cabal work
-      id:   cabal-local
-      uses: actions/cache@v2
-      with:
-        path: |
-          dist-newstyle
-        key: ${{ runner.os }}-8.10.4-3.2-cabal-local
-
-    - name: Install dependencies
-      run: |
-          cabal v2-update
-          cabal v2-build --dependencies-only --enable-tests --disable-optimization
-
-    - name: Test pdf creation with pdf-engine
-      run: |
-          cabal v2-run --disable-optimization pandoc -- --pdf-engine=${{ matrix.pdfengine }} -o out.pdf doc/getting-started.md
-
   windows:
 
     runs-on: windows-2019