Remove Python 3.8 from various places

[gshank]

Resolves #

Problem

Solution

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 or 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.

[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

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 89.13%. Comparing base (d18f50b) to head (31f9a35).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10861      +/-   ##
==========================================
- Coverage   89.19%   89.13%   -0.07%     
==========================================
  Files         183      183              
  Lines       23434    23434              
==========================================
- Hits        20903    20888      -15     
- Misses       2531     2546      +15     

Flag	Coverage Δ
integration	86.41% <0.00%> (-0.16%)	⬇️
unit	62.12% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Unit Tests	62.12% <0.00%> (ø)
Integration Tests	86.41% <0.00%> (-0.16%)	⬇️

[gshank]

I don't see why "unit test / python 3.8" was trying to run.

[peterallenwebb]

Ran the Tests and Code Checks pipeline successfully with these changes: https://github.com/dbt-labs/dbt-core/actions/runs/11371519059

[gshank]

It won't let us merge with that failing "unit test / python 3.8". Also I'm wondering if there's anything that needs to be done about codecov?