Use python3 -m pytest instead of pytest to run the tests

Makefile

@@ -42,7 +42,7 @@ unit-tests:
 		pip install --no-cache-dir -r tests/python/unit/requirements.txt; \
 		pip install --no-cache-dir -r code-env/python/spec/requirements.txt; \
 		export PYTHONPATH="$(PYTHONPATH):$(PWD)/python-lib"; \
-		pytest tests/python/unit --alluredir=tests/allure_report || ret=$$?; exit $$ret \
+		python3 -m pytest tests/python/unit --alluredir=tests/allure_report || ret=$$?; exit $$ret \
 	)
 
 integration-tests:
@@ -53,7 +53,7 @@ integration-tests:
 		source env/bin/activate; \
 		pip3 install --upgrade pip;\
 		pip install --no-cache-dir -r tests/python/integration/requirements.txt; \
-		pytest tests/python/integration --alluredir=tests/allure_report || ret=$$?; exit $$ret \
+		python3 -m pytest tests/python/integration --alluredir=tests/allure_report || ret=$$?; exit $$ret \
 	)
 
 tests: unit-tests integration-tests