Release candidate v3.5

[danielhuppmann]

Description of PR

This PR adds the highlights and API changes to the release notes and removes an attribute after switching from subannual to datetime format.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.7%. Comparing base (134081a) to head (e97f292).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pyam/core.py	0.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #994     +/-   ##
=======================================
- Coverage   94.7%   94.7%   -0.1%     
=======================================
  Files         70      70             
  Lines       6757    6759      +2     
=======================================
  Hits        6403    6403             
- Misses       354     356      +2     

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[danielhuppmann]

Successfully deployed on test.pypi.org

[danielhuppmann]

Successfully deployed on test.pypi.org

That was too quick, it didn't deploy on test.pypi.org