use nf-core tools isort settings in pipeline template

[fabianegli]

If we want to have consistent Python formatting in the nf-core ecosystem, isort should be part of that.

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

[codecov]

Codecov Report

Merging #1792 (6fabd3a) into dev (f105f49) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev    #1792   +/-   ##
=======================================
  Coverage   69.25%   69.25%           
=======================================
  Files          59       59           
  Lines        7148     7148           
=======================================
  Hits         4950     4950           
  Misses       2198     2198           

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