fix for stopping dags in terminal state

[patkivikram]

Description

Fix to not call stop for DAG's in terminal states
Fixes #51

Type of Change

• Bug Fix
• New Feature
• Breaking Change
• Refactor
• Documentation
• Other (please describe)

Checklist

• I have read the contributing guidelines
• Existing issues have been referenced (where applicable)
• I have verified this change is not present in other open pull requests
• Functionality is documented
• All code style checks pass
• New code contribution is covered by automated tests
• All new and existing tests pass

[codecov]

Codecov Report

Merging #52 (5844c11) into main (35a0b1e) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #52   +/-   ##
=======================================
  Coverage   86.51%   86.51%           
=======================================
  Files          12       12           
  Lines        1824     1824           
  Branches      215      215           
=======================================
  Hits         1578     1578           
  Misses        146      146           
  Partials      100      100           

Files	Coverage Δ
dagger/tasks/task.py	79.37% <ø> (ø)