ADD Support of SMBClient for External storage

It might be nice to support SMBClient for External storage.
It could be possible just by adding smbclient package.

Dockerfile

@@ -12,6 +12,7 @@ RUN apt-get update && apt-get install -y \
   libpng12-dev \
   libpq-dev \
   libxml2-dev \
+  smbclient \
   && rm -rf /var/lib/apt/lists/*
 
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