Update Dockerfile

- closes https://github.com/assimp/assimp/issues/5403

Dockerfile

@@ -6,6 +6,7 @@ RUN apt-get update && apt-get install -y ninja-build \
 RUN add-apt-repository ppa:ubuntu-toolchain-r/test && apt-get update 
 
 WORKDIR /opt
+RUN apt install zlib1g-dev
 
 # Build Assimp
 RUN git clone https://github.com/assimp/assimp.git /opt/assimp