Run nox -s scripts in the scheduled tests

[agriyakhetarpal]

Description

This PR adds a job step for testing the example scripts nightly (we weren't testing the example scripts in the scheduled tests workflow after #3264 and #3279)

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.05% 🎉

Comparison is base (7cba890) 99.55% compared to head (e4cb2a4) 99.60%.
Report is 29 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3345      +/-   ##
===========================================
+ Coverage    99.55%   99.60%   +0.05%     
===========================================
  Files          253      253              
  Lines        19553    19546       -7     
===========================================
+ Hits         19466    19469       +3     
+ Misses          87       77      -10     

Files Changed	Coverage Δ
pybamm/solvers/solution.py	100.00% <ø> (ø)
pybamm/experiment/experiment.py	100.00% <100.00%> (ø)
pybamm/parameters/bpx.py	99.49% <100.00%> (+4.73%)	⬆️
pybamm/simulation.py	100.00% <100.00%> (ø)
pybamm/step/_steps_util.py	100.00% <100.00%> (ø)

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[Saransh-cpp]

Thanks, @agriyakhetarpal! Could you merge develop once to fix the failing CI?