fix: double hashing of access token signature

[hperl]

Related issue(s)

Fixes #3485

Checklist

• I have read the contributing guidelines.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I am following the
  contributing code guidelines.
• 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 the 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 or changed the documentation.

Further Comments

[codecov]

Codecov Report

Merging #3486 (ba90123) into master (0448284) will decrease coverage by 0.03%.
The diff coverage is n/a.

❗ Current head ba90123 differs from pull request most recent head 02f4fe1. Consider uploading reports for the commit 02f4fe1 to get more accurate results

@@            Coverage Diff             @@
##           master    #3486      +/-   ##
==========================================
- Coverage   76.84%   76.82%   -0.03%     
==========================================
  Files         124      124              
  Lines        9174     9173       -1     
==========================================
- Hits         7050     7047       -3     
- Misses       1674     1677       +3     
+ Partials      450      449       -1     

Impacted Files	Coverage Δ
persistence/sql/persister_oauth2.go	81.43% <ø> (-0.83%)	⬇️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.