Fix the following security issues caused by usage of old werkzeug library

[tisnik]

Affected file: requirements.txt

CVE detail: CVE-2019-14806 More information high severity Vulnerable versions: < 0.15.3 Patched version: 0.15.3

Pallets Werkzeug before 0.15.3, when used with Docker, has insufficient debugger PIN randomness because Docker containers share the same machine id.