Fix json schema

[b-butler]

Description

Fixes warnings from jsonschema.

Motivation and Context

Removes warning from test and use of flow.

Checklist:

• I am familiar with the Contributing Guidelines.
• I agree with the terms of the Contributor Agreement.
• My name is on the list of contributors.
• The changes introduced by this pull request are covered by existing or newly introduced tests.
• The package documentation and framework documentation in signac-docs are up to date with these changes.
• I have updated the changelog and added any related issue and pull request numbers for future reference.

[codecov]

Codecov Report

Merging #787 (5ed67c7) into main (39b51c3) will decrease coverage by 0.14%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #787      +/-   ##
==========================================
- Coverage   69.25%   69.11%   -0.14%     
==========================================
  Files          45       45              
  Lines        4348     4348              
  Branches     1055     1055              
==========================================
- Hits         3011     3005       -6     
- Misses       1131     1137       +6     
  Partials      206      206              

Files	Coverage Δ
flow/project.py	82.78% <ø> (-0.39%)	⬇️