add pip dev index

Created by: kazaamjt

Description

Makes vyos module testing use the pip dev index

Self Check:

Strike through any lines that are not applicable (~~line~~) then check the box

• Attached issue to pull request
• Changelog entry
• Version number is bumped to dev version
• Code is clear and sufficiently documented
• Sufficient test cases (reproduces the bug/tests the requested feature)
• Correct, in line with design
• End user documentation is included or an issue is created for end-user documentation (add ref to issue here: )

Reviewer Checklist:

• Sufficient test cases (reproduces the bug/tests the requested feature)
• Code is clear and sufficiently documented
• Correct, in line with design