Fix LibreOffice targz link in Dockerfile

Dockerfile

@@ -8,7 +8,7 @@ RUN apt-get install -y -q libsm6 libcups2 libcairo2 libdbus-1-3 libxinerama1
 
 WORKDIR /tmp
 RUN wget https://github.com/jgm/pandoc/releases/download/2.7.3/pandoc-2.7.3-1-amd64.deb
-RUN wget https://download.documentfoundation.org/libreoffice/stable/6.3.3/deb/x86_64/LibreOffice_6.3.3_Linux_x86-64_deb.tar.gz
+RUN wget https://download.documentfoundation.org/libreoffice/stable/6.4.1/deb/x86_64/LibreOffice_6.4.1_Linux_x86-64_deb.tar.gz
 RUN tar xvzf LibreOffice_6.3.3_Linux_x86-64_deb.tar.gz