Fix alignment of source in submission row

[20wildmanj]

Previously, the upload source name in a student's submissions row for an assessment wasn't vertically aligned with the rest of the row. Just added some styling to make it centered.

Before:

After:

How Has This Been Tested?

• Go to an assessment, make a submission / view submissions, and see that the submission source is vertically aligned.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have run rubocop for style check. If you haven't, run overcommit --install && overcommit --sign to use pre-commit hook for linting
• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, included in this PR

Other issues / help required

If unsure, feel free to submit first and we'll help you along.

[damianhxy]

Confirmed vertical alignment

lgtm!