Try some more dependencies

x86_64-linux-deb9/Dockerfile

@@ -21,7 +21,7 @@ RUN apt-get update -qq && apt-get install --no-install-recommends -qy \
     # DWARF libraries
     libdw1 libdw-dev \
     # Documentation tools
-    python3-sphinx texlive-xetex texlive-latex-extra texlive-binaries \
+    python3-sphinx texlive-xetex texlive-latex-extra texlive-binaries texlive-fonts-recommended lmodern \
     cabal-install-2.4 ghc-8.4.4 \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*