maint: use release instead of regenesis branches

[smartcontracts]

Description
Changes our branching model to use release/ branches instead of
regenesis/ branches now that we no longer plan to perform any
regenesis-style upgrades. Using release/ branches will reduce confusion
from people who see a regenesis/ branch and assume (logically) that this
branch will result in a regenesis.

[changeset-bot]

⚠️ No Changeset found

Latest commit: db0e585

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[smartcontracts]

Note: this is part of tech proposal #34 on slack.

[codecov-commenter]

Codecov Report

Merging #2279 (db0e585) into develop (dfd5ac6) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #2279   +/-   ##
========================================
  Coverage    80.08%   80.08%           
========================================
  Files           77       77           
  Lines         2460     2460           
  Branches       450      450           
========================================
  Hits          1970     1970           
  Misses         490      490           

Flag	Coverage Δ
contracts	99.29% <ø> (ø)
core-utils	86.77% <ø> (ø)
data-transport-layer	49.72% <ø> (ø)
sdk	55.75% <ø> (ø)

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