Update VulnTotal Github Datasource

[michaelehab]

Fix #1499

There was an incorrect import path in the vulntotal/datasources/github.py file. The previous import statement:

from fetchcode.package_versions import github_response

it was updated to:

from fetchcode.utils import github_response

[keshav-space]

@michaelehab We don't need this change yet since we're still using v0.3.0 of fetchcode in VulnerableCode. https://github.com/nexB/vulnerablecode/blob/433d3a65e13d1de77d17c8ee627aca7283da0a09/requirements.txt#L116 VulnTotal and VulnerableCode share the same version of dependency. In your local installation you can use v0.3.0 of fetchcode. If you want to use the latest version of fetchcode you can make change to your import locally.

[michaelehab]

@keshav-space Thank you for the clarification; I will proceed with version 0.3.0.