change workflow trigger

[emmyoop]

resolves #8414
docs dbt-labs/docs.getdbt.com/#

Problem

PRs that were merged before the workflow were not generating issues.

Solution

Trigger off pull_request_target.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.

[codecov]

Codecov Report

Merging #8418 (597bcae) into main (17cd145) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #8418      +/-   ##
==========================================
- Coverage   86.33%   86.31%   -0.03%     
==========================================
  Files         174      174              
  Lines       25561    25561              
==========================================
- Hits        22069    22062       -7     
- Misses       3492     3499       +7     

Flag	Coverage Δ
integration	83.09% <ø> (-0.03%)	⬇️
unit	65.14% <ø> (ø)

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see 2 files with indirect coverage changes