Maintainers needed

It seems like excalibur is dead:

- 7 sept 20202
- Last [PyPI release](https://pypi.org/project/excalibur-py/): 2020-03-21 - @vinayak-mehta is the only owner
- Several PRs which look ready to be merged, but are still open
- Current release seems to be broken on modern systems. (win 10 refresh issue)

Only 10 contributors on the project.
New contributors are unable to open a PR.

Please update repo settings so others can open PR's.
Now there is an error:
`Pull request creation failed. Validation failed: must be a collaborator`

@MartinThoma , @vinayak-mehta

Review the repository settings and the open pull requests mentioned in the issue. Confirm whether contributors without collaborator access can create pull requests; done means the reported validation error no longer prevents new contributors from opening one.

Written by the indexing model from the issue text.