Use tuples to perform swap in `Permutations`

[atifaziz]

This PR refactors swaps in Permutations to use tuples, which reads simpler and more succinct.

[codecov[bot]]

Codecov Report

Merging #925 (583c51b) into master (096e00f) will decrease coverage by 0.00%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #925      +/-   ##
==========================================
- Coverage   92.44%   92.43%   -0.01%     
==========================================
  Files         112      112              
  Lines        3440     3436       -4     
  Branches     1019     1019              
==========================================
- Hits         3180     3176       -4     
  Misses        199      199              
  Partials       61       61              

Impacted Files	Coverage Δ
MoreLinq/Permutations.cs	96.77% <100.00%> (-0.20%)	:arrow_down:

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more