Hardcode dbt version for project fixture in repository unit tests

[QMalcolm]

resolves #10056

Problem

Letting the dbt version be dynamic in the project fixture previously was causing some tests to break whenever the version of dbt actually got updated, which isn't great. It'd be super annoying to have to always update tests affected by this. To get around this we've gone and hard coded the dbt version in the profile. The alternative was to interpolate the version during comparison during the relevant tests, which felt less appealing.

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
• This PR includes type annotations for new and modified functions

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.19%. Comparing base (f6b2cb7) to head (e43b624).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10059      +/-   ##
==========================================
- Coverage   88.20%   88.19%   -0.01%     
==========================================
  Files         181      181              
  Lines       22665    22665              
==========================================
- Hits        19991    19989       -2     
- Misses       2674     2676       +2     

Flag	Coverage Δ
integration	85.57% <ø> (+<0.01%)	⬆️
unit	62.31% <ø> (ø)

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