Remove subprocess requirement

Author: elliottmurray

docker/py36.Dockerfile

@@ -6,7 +6,7 @@ COPY requirements_dev.txt .
 
 RUN apk add gcc py-pip python-dev libffi-dev openssl-dev gcc libc-dev make
 
-RUN python -m pip install psutil subprocess32
+RUN python -m pip install psutil
 RUN pip install -r requirements_dev.txt
 
 CMD tox -e py36

docker/py37.Dockerfile

@@ -6,7 +6,7 @@ COPY requirements_dev.txt .
 
 RUN apk add gcc py-pip python-dev libffi-dev openssl-dev gcc libc-dev make
 
-RUN python -m pip install psutil subprocess32
+RUN python -m pip install psutil
 RUN pip install -r requirements_dev.txt
 
 CMD tox -e py37

docker/py38.Dockerfile

@@ -6,7 +6,7 @@ COPY requirements_dev.txt .
 
 RUN apk add gcc py-pip python-dev libffi-dev openssl-dev gcc libc-dev make
 
-RUN python -m pip install psutil subprocess32
+RUN python -m pip install psutil
 RUN pip install -r requirements_dev.txt
 
 CMD tox -e py38