chore(toolkit-lib): revert back to nock@13 for more stable tests

[mrgrain]

Fixes unstable tests sometimes timing out or failing with TypeError: this._getSession is not a function

Seems to come down to this report:
mswjs/interceptors#675

But in general nock v14 seems to have a lot of problems:
nock/nock#2857
nock/nock#2855
nock/nock#2849
nock/nock#2846
nock/nock#2839
nock/nock#2832
nock/nock#2828

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.30%. Comparing base (6f1df5d) to head (ab1ec01).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #436      +/-   ##
==========================================
+ Coverage   79.15%   79.30%   +0.14%     
==========================================
  Files          54       54              
  Lines        6889     6889              
  Branches      773      781       +8     
==========================================
+ Hits         5453     5463      +10     
+ Misses       1418     1406      -12     
- Partials       18       20       +2     

Flag	Coverage Δ
suite.unit	79.30% <ø> (+0.14%)	⬆️

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