Fix summarised_competencies CI issues

[MakisH]

In the summarized_competencies.md:

• Removes the duplicate commented-out list of authors (the comment needs to be in YAML anyway)
• Replaces "University of Würzburg" with https://github.com/the-teachingRSE-project as affiliation.
• Fix an assertion regarding the initials not appearing in the acknowledgments list (replaces it with We, renders normally)
• Update the .gitignore

Motivated by the CI failing for the pull request #362 (not for the branch, but for the merged result).

[CaptainSifff]

Thank you for picking this up!