Corrected commands to test python app

Jenkinsfile

@@ -17,8 +17,9 @@ pipeline {
                     dir('api') {
                         sh '''
                             python3 -m venv env
-                            env/bin/pip install -r requirements.txt pytest
-                            env/bin/pytest . --junit-xml=pytest_junit.xml
+                            source env/bin/activate
+                            pip install -r requirements.txt pytest
+                            python3 -m pytest --junit-xml=pytest_junit.xml
                         '''
                     }
                 }