Improve SlurmManager readability, add env inheritance

[nefrathenrici]

Purpose

To-do

Content

---

• I have read and checked the items on the review checklist.

[codecov]

Codecov Report

Attention: Patch coverage is 9.78261% with 83 lines in your changes missing coverage. Please review.

Project coverage is 17.04%. Comparing base (4152174) to head (a62386e).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/workers.jl	0.00%	82 Missing ⚠️
src/backends.jl	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #123      +/-   ##
==========================================
- Coverage   17.19%   17.04%   -0.15%     
==========================================
  Files           9        9              
  Lines         506      528      +22     
==========================================
+ Hits           87       90       +3     
- Misses        419      438      +19     

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