Preparation for release candidate 0.35.0

[lillian542]

Updates PennyLane as we're entering a new development version (release of v0.35.0 coming up):

Preparation of release candidate:

• Rename changelog-dev.md to changelog-0.35.0.md
• Increments the version number to v0.35.0
• Change changelog-dev reference to changelog-0.35 reference in release_notes.md

rc    master
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|     - add changelog-dev.md, add changelog-dev reference to release_notes.md, bump version to 0.36.0-dev
|    /
|   /
|  /
| /
|/
- (**THIS PR**) rename changelog-dev.md to changelog-0.35.0.md, change changelog-dev reference to changelog-0.35 reference in release_notes.md, move "current release" label from changelog-0.34 to changelog-0.35, change version from 0.35.0-dev to 0.35.0
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[github-actions[bot]]

Hello. You may have forgotten to update the changelog! Please edit doc/releases/changelog-dev.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[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.67%. Comparing base (2ae851b) to head (2f202f7).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5257      +/-   ##
==========================================
- Coverage   99.68%   99.67%   -0.01%     
==========================================
  Files         399      399              
  Lines       36871    36585     -286     
==========================================
- Hits        36754    36467     -287     
- Misses        117      118       +1     

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