update jenkinsfile and dockerfile

Dockerfile

@@ -1,9 +1,8 @@
 FROM python:3.5.6
 
 COPY ./requirements.txt ./requirements.txt
-RUN pip install --user --upgrade pip
-RUN pip install --user -r requirements.txt
-ADD . /code
-WORKDIR /code/
+RUN pip install --upgrade pip
+RUN pip install -r requirements.txt
 RUN pip install pytest
-CMD ["pytest"]
+ADD . /code
+WORKDIR /code

Jenkinsfile

@@ -1,12 +1,6 @@
 pipeline {
     agent { docker { image 'python:3.5.6' } }
     stages {
-        stage('build') {
-            steps {
-                sh 'pip install --user -r requirements.txt'
-                sh 'pip install pytest'
-            }
-        }
         stage('test') {
             steps {
                 sh 'python -m pytest'