Fix lightning stable plugin test matrix tests

[AmintorDusko]

Context: Lightning stable version is incompatible with the latest Scipy version.

Description of the Change: We add a downgrade scipy version for some of the latest tests.

Benefits:

Possible Drawbacks:

Related GitHub Issues:

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.88%. Comparing base (84b5da5) to head (cfefe99).
Report is 95 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (84b5da5) and HEAD (cfefe99). Click for more details.

HEAD has 105 uploads less than BASE

Flag	BASE (84b5da5)	HEAD (cfefe99)
	109	4

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #783       +/-   ##
===========================================
- Coverage   91.89%   27.88%   -64.01%     
===========================================
  Files         126       17      -109     
  Lines       18490     1886    -16604     
===========================================
- Hits        16991      526    -16465     
+ Misses       1499     1360      -139     

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[AmintorDusko]

Links to tests:

• latest-stable
• stable-stable

[maliasadi]

latest-stable is still failing due to MCM updates in the PL latest! I'd say this is not related to your PR and will be fixed with the next release. right?
stable-stable PASS :)

[AmintorDusko]

latest-stable is still failing due to MCM updates in the PL latest! I'd say this is not related to your PR and will be fixed with the next release. right? stable-stable PASS :)

Yes.

[maliasadi]

🙌

[AmintorDusko]

🙌

Thank you, @maliasadi!

[vincentmr]

LGTM, thanks @AmintorDusko .

[AmintorDusko]

LGTM, thanks @AmintorDusko .

Thank you, @vincentmr!