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	eb91d4d
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/69b1098ba87d4b0008f4635b

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.01%. Comparing base (90df884) to head (eb91d4d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1452   +/-   ##
=======================================
  Coverage   90.01%   90.01%           
=======================================
  Files          67       67           
  Lines        4769     4769           
  Branches      885      885           
=======================================
  Hits         4293     4293           
  Misses        458      458           
  Partials       18       18           

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