fix(ci): bump release workflow to OTP 28.5

[yordis]

• OTP 28.0 ships a :re module that is incompatible with hex 2.4.2 (:re.import/1 undefined), breaking mix hex.publish during the release workflow.

[cursor]

PR Summary

Low Risk
Single CI toolchain pin change with no application or runtime code impact.

Overview
Updates the Hexpm Release workflow (release.yml) so erlef/setup-beam installs OTP 28.5 instead of 28.0, while Elixir stays at 1.19.0.

This unblocks mix hex.publish on release: OTP 28.0’s :re module breaks hex 2.4.2 (:re.import/1 undefined), which the publish job hits after mix local.hex.

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[Copilot]

Pull request overview

This PR updates the Hex release GitHub Actions workflow to run on a newer Erlang/OTP patch level to avoid the OTP 28.0 :re incompatibility that breaks mix hex.publish, keeping releases functional.

Changes:

• Bump otp-version used by the Hex release workflow from 28.0 to 28.5.

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