chore: license checker

[kevgo]

Makes a license checker available locally and as a CI job.

Related Issue or Design Document

https://github.com/ory-corp/general/issues/603

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security vulnerability.
  If this pull request addresses a security vulnerability,
  I confirm that I got approval (please contact security@ory.sh) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works.
• I have added the necessary documentation within the code base (if appropriate).

[codecov]

Codecov Report

Merging #3328 (816fea7) into master (c752125) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3328      +/-   ##
==========================================
- Coverage   76.86%   76.84%   -0.03%     
==========================================
  Files         123      123              
  Lines        8913     8913              
==========================================
- Hits         6851     6849       -2     
- Misses       1635     1636       +1     
- Partials      427      428       +1     

Impacted Files	Coverage Δ
persistence/sql/persister_oauth2.go	82.12% <0.00%> (-0.77%)	⬇️

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