fix: pip-sample/testing_requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-DJANGO-6041515
- https://snyk.io/vuln/SNYK-PYTHON-TORNADO-6041512
- https://snyk.io/vuln/SNYK-PYTHON-WERKZEUG-6041510

pip-sample/testing_requirements.txt

@@ -55,14 +55,14 @@ simplegeneric==0.8.1
 six==1.11.0
 terminado==0.8.1
 testpath==0.4.1
-tornado==5.1.1
+tornado==6.3.3
 traitlets==4.3.2
 tweepy==3.6.0
 urllib3==1.26.5
 virtualenv==16.0.0
 wcwidth==0.1.7
 webencodings==0.5.1
-Werkzeug==0.15.3
+Werkzeug==3.0.1
 widgetsnbextension==3.4.2
 xlrd==1.1.0
-django==3.2.16
+django==3.2.23