bump pennylane requirement to v0.40

[josephleekl]

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[github-actions]

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Please edit .github/CHANGELOG.md with:

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.36%. Comparing base (d8461f3) to head (cdd4007).
Report is 4 commits behind head on v0.40.0_rc.

❗ There is a different number of reports uploaded between BASE (d8461f3) and HEAD (cdd4007). Click for more details.

HEAD has 113 uploads less than BASE

Flag	BASE (d8461f3)	HEAD (cdd4007)
	119	6

Additional details and impacted files

@@               Coverage Diff               @@
##           v0.40.0_rc    #1033       +/-   ##
===============================================
- Coverage       97.93%   27.36%   -70.58%     
===============================================
  Files             233       29      -204     
  Lines           39988     2646    -37342     
===============================================
- Hits            39162      724    -38438     
- Misses            826     1922     +1096     

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[multiphaseCFD]

Thanks @josephleekl. Don't forget to change the version from rc{n} to rc{n+1}.