chore: update CODEOWNERS

[notmandatory]

Description

Update to use new @bitcoindevkit/chain maintainers group. This will make it easier to update maintainers going forward.

Notes to the reviewers

If you're in the new @bitcoindevkit/chain group you'll be notified when new PRs or issues are created.

Checklists

All Submissions:

• I followed the contribution guidelines

[luisschwab]

ACK a0f958a

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.84%. Comparing base (2c89f60) to head (a0f958a).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2355   +/-   ##
=======================================
  Coverage   78.84%   78.84%           
=======================================
  Files          31       31           
  Lines        6060     6060           
  Branches      288      288           
=======================================
  Hits         4778     4778           
  Misses       1203     1203           
  Partials       79       79           

Flag	Coverage Δ
rust	78.84% <ø> (ø)

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[noahjoeris]

ACK a0f958a