Resolve "[Hotfix]: venv should be activated before the shell script is run"

Closes #3 (closed)

\approve @ds @gislars

Dockerfile

@@ -33,7 +33,7 @@ WORKDIR /srv/rabotnik
 
 # Install rabotnik with its dependencies
 RUN python3 -m venv venv && . venv/bin/activate && \
-    pip3 install --upgrade wheel setuptools pip && \
+    pip3 install --upgrade wheel setuptools pip mercantile && \
     pip3 config set global.extra-index-url https://git.gfz-potsdam.de/api/v4/projects/2940/packages/pypi/simple && \
     pip3 install https://git.gfz-potsdam.de/globaldynamicexposure/rabotnik/rabotnik/-/archive/master/rabotnik-master.zip
 
@@ -44,4 +44,4 @@ RUN apt-get autoremove --yes $build_dependencies && apt-get autoremove --yes &&
 # Set up start script
 COPY ./files/start.sh /usr/local/bin
 
-CMD /usr/local/bin/start.sh
+CMD . venv/bin/activate && /usr/local/bin/start.sh