chore(ci): add FOSSA workflow

[evansims]

Description

This PR adds a CI GitHub workflow for our FOSSA tooling.

References

openfga/sdk-generator#390

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.72%. Comparing base (ebc243f) to head (874ce3d).

Additional details and impacted files

@@            Coverage Diff            @@
##               main      #93   +/-   ##
=========================================
  Coverage     27.72%   27.72%           
  Complexity      785      785           
=========================================
  Files           158      158           
  Lines          5862     5862           
  Branches        639      639           
=========================================
  Hits           1625     1625           
  Misses         4161     4161           
  Partials         76       76           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.