fix: add kid to verifiable credential header

[hperl]

Related issue(s)

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 #3606 (96ec017) into master (c004fee) will decrease coverage by 0.02%.
Report is 1 commits behind head on master.
The diff coverage is 57.14%.

❗ Current head 96ec017 differs from pull request most recent head 5ed5f67. Consider uploading reports for the commit 5ed5f67 to get more accurate results

@@            Coverage Diff             @@
##           master    #3606      +/-   ##
==========================================
- Coverage   76.28%   76.26%   -0.02%     
==========================================
  Files         132      132              
  Lines        9984     9990       +6     
==========================================
+ Hits         7616     7619       +3     
- Misses       1848     1850       +2     
- Partials      520      521       +1     

Files Changed	Coverage Δ
oauth2/handler.go	67.42% <57.14%> (-0.21%)	⬇️