FIX sed command on Dockerfile now has the correct path and makes changes inline

Dockerfile

@@ -26,7 +26,7 @@ RUN python3 -m venv ./venv
 RUN . ./venv/bin/activate
 RUN ./venv/bin/pip install --upgrade pip setuptools
 RUN ./venv/bin/pip install -r ./requirements.txt
-#RUN sed "s/python3.8/python$pyversion/g" prog_calc.wsgi
+RUN sed -i "s/python3.8/python$pyversion/g" ../prog_calc.wsgi
 
 # Configure Apache
 USER root