chore: add release planning template

[jescalada]

Adds a template for release planning, which is the solution we discussed during the last community meeting (#1416) regarding #1442 (release process improvements/feature branches).

Feel free to edit/add sections as appropriate!

[netlify]

✅ Deploy Preview for endearing-brigadeiros-63f9d0 canceled.

Name	Link
🔨 Latest commit	d4e994e
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/69c1598638a1120007e8aa53

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.66%. Comparing base (68bf3db) to head (d4e994e).
⚠️ Report is 31 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1452   +/-   ##
=======================================
  Coverage   89.66%   89.66%           
=======================================
  Files          68       68           
  Lines        4869     4869           
  Branches      888      888           
=======================================
  Hits         4366     4366           
  Misses        485      485           
  Partials       18       18           

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[jescalada]

Closing this as no longer relevant based on #1483 and discussion on #1454