Fix PowerShell syntax error of quotes (Fixes #3908)

[gghhffyy368]

Description

This PR fixes a syntax error generated by mamba shell hook in PowerShell where the quotes in third line of output causes the problem. This PR attempts to use "& " to run commands represented by strings in Powershell. I compiled this change on my PC with Visual Studio 17 2022 and it solved that problem.

Type of Change

• Bugfix
• Feature / enhancement
• CI / Documentation
• Maintenance

Checklist

• My code follows the general style and conventions of the codebase, ensuring consistency
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run pre-commit run --all locally in the source folder and confirmed that there are no linter errors.
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes

---

Fixes #3908

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.74%. Comparing base (a3c2580) to head (c21c885).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
libmamba/src/core/activation.cpp	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4179      +/-   ##
==========================================
- Coverage   54.75%   54.74%   -0.01%     
==========================================
  Files         240      240              
  Lines       30145    30147       +2     
  Branches     3214     3215       +1     
==========================================
  Hits        16505    16505              
- Misses      13637    13639       +2     
  Partials        3        3              

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