bump up version of networkx

Author: tomvanmele

requirements.txt

@@ -6,7 +6,7 @@ matplotlib >= 2.2, < 3.0; python_version >= '2.7' and python_version < '3.0'
 matplotlib >= 2.2, < 3.1; python_version >= '3.5' and python_version <= '3.7' and sys_platform == 'win32'
 matplotlib >= 3.1; python_version >= '3.8' and sys_platform == 'win32'
 matplotlib >= 2.2; python_version >= '3.5' and sys_platform != 'win32'
-networkx
+networkx >= 3.0
 numpy >= 1.15.4
 pillow
 schema