Dockerfile: run the french version of Laby.

Dockerfile

@@ -25,4 +25,4 @@ RUN apt-get remove -y inkscape \
 
 RUN apt-get -y -q autoclean && apt-get -y -q autoremove 
 
-ENTRYPOINT ["/usr/games/laby"]
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+ENTRYPOINT ["/usr/games/laby", "--lang=fr"]
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