minor changes

Author: ypriverol

Dockerfile

@@ -15,7 +15,7 @@ RUN mkdir -p /tool/source
 RUN git config --global http.sslVerify false
 RUN git clone --depth 1 https://github.com/bigbio/py-pgatk.git /tool/source
 WORKDIR /tool/source
-RUN pip3 install --upgrade pip && pip3 install -r requirements.txt && pip3 install -e .
+RUN pip3 install --no-cache-dir -r requirements.txt && pip3 install --no-cache-dir -e .
 
 ENV LC_ALL=C.UTF-8
 ENV LANG=C.UTF-8