Update install instructions for LGPU

[CatalinaAlbornoz]

Update install instructions for LGPU. Added instructions to install PennyLane latest.

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit .github/CHANGELOG.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.36%. Comparing base (7f2d585) to head (888c1fa).
Report is 1 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (7f2d585) and HEAD (888c1fa). Click for more details.

HEAD has 7 uploads less than BASE

Flag	BASE (7f2d585)	HEAD (888c1fa)
	13	6

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #1037       +/-   ##
===========================================
- Coverage   97.15%   27.36%   -69.79%     
===========================================
  Files         233       29      -204     
  Lines       39079     2646    -36433     
===========================================
- Hits        37966      724    -37242     
- Misses       1113     1922      +809     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[AmintorDusko]

Nice job @CatalinaAlbornoz. Contributions like that are always super helpful!

[maliasadi]

Thanks @CatalinaAlbornoz!