Resolve MyPy errors in Cosmos pre-commit

[abhi12mohan]

Description

Resolves all MyPy pre-commit errors. "type: ignore" comments used sparingly and only when needed, i.e. a MyPy solution currently does not exist or deeper code changes need to be made.

Closes: #301

Checklist

• I have made corresponding changes to the documentation (if required)
• I have added tests that prove my fix is effective or that my feature works

[netlify]

👷 Deploy Preview for amazing-pothos-a3bca0 processing.

Name	Link
🔨 Latest commit	892f784
🔍 Latest deploy log	https://app.netlify.com/sites/amazing-pothos-a3bca0/deploys/64bedca167846e00080ffa6e

[codecov]

Codecov Report

Patch coverage: 92.55% and project coverage change: -0.05% ⚠️

Comparison is base (f153c49) 91.26% compared to head (cfb2123) 91.21%.

❗ Current head cfb2123 differs from pull request most recent head 892f784. Consider uploading reports for the commit 892f784 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #377      +/-   ##
==========================================
- Coverage   91.26%   91.21%   -0.05%     
==========================================
  Files          46       46              
  Lines        1579     1605      +26     
==========================================
+ Hits         1441     1464      +23     
- Misses        138      141       +3     

Files Changed	Coverage Δ
cosmos/operators/local.py	80.83% <78.57%> (-0.34%)	⬇️
cosmos/converter.py	98.50% <87.50%> (-1.50%)	⬇️
cosmos/dbt/selector.py	98.61% <88.88%> (-1.39%)	⬇️
cosmos/operators/docker.py	69.76% <92.30%> (ø)
cosmos/operators/kubernetes.py	72.04% <96.55%> (ø)
cosmos/__init__.py	100.00% <100.00%> (ø)
cosmos/airflow/dag.py	100.00% <100.00%> (ø)
cosmos/airflow/graph.py	100.00% <100.00%> (ø)
cosmos/airflow/task_group.py	100.00% <100.00%> (ø)
cosmos/core/airflow.py	93.33% <100.00%> (-0.42%)	⬇️
... and 9 more

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[tatiana]

Thank you very mich, @abhi12mohan ! It's looking very good. It's a relief to have the type checks in place. I left some minor comments in-line.

[tatiana]

@abhi12mohan, thank you very much for addressing the feedback and creating #382 to follow up on the issues that were ignored in this initial support to MyPy.

Once we rebase and resolve the conflicts, we can merge this PR!

[tatiana]

Thanks, @abhi12mohan , one last comment - and we can merge! 🎉