add typing to partially typed methods in runnable.py

[MichelleArk]

resolves #8402
docs dbt-labs/docs.getdbt.com/#

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/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

Patch coverage: 100.00% and project coverage change: -0.03% ⚠️

Comparison is base (7e2a08f) 86.41% compared to head (d9a21d8) 86.39%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8569      +/-   ##
==========================================
- Coverage   86.41%   86.39%   -0.03%     
==========================================
  Files         174      174              
  Lines       25587    25587              
==========================================
- Hits        22112    22106       -6     
- Misses       3475     3481       +6     

Flag	Coverage Δ
integration	83.20% <100.00%> (-0.11%)	⬇️
unit	65.04% <63.63%> (ø)

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

Files Changed	Coverage Δ
core/dbt/task/runnable.py	92.03% <100.00%> (ø)

... and 2 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[emmyoop]

LGTM