Deprecate releasing a realtime channel that isn't detached (RTS4b) - #1250

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: ably/sdk-upload-action@4e694297f208b72b5a9f6b1248a1556f19f821d6, actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5, actions/setup-java@c1e323688fd81a25caa38c78aa6df2d33d3e20d9, aws-actions/configure-aws-credentials@67fbcbb121271f7775d2e7715933280b06314838, gradle/actions/setup-gradle@d9c87d481d55275bb5441eef3fe0e46805f9ef70. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Failed to restore gradle-home-v1|Linux|build[58168bc1e5156c8da5e870236cc5d0b0]-17607fb6d48b50c26792922ddad4be1cdcb41bc6: Error: Cache service responded with 400

The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/