Add omni bencher & chain-spec-builder bins to release (#4557)
Closes: https://github.com/paritytech/polkadot-sdk/issues/4354 This PR adds the steps to build and attach `frame-omni-bencher` and `chain-spec-builder` binaries to the release draft ## TODO - [x] add also chain-spec-builder binary - [ ] ~~check/investigate Kian's comment: `chain spec builder. Ideally I want it to match the version of the sp-genesis-builder crate`~~ see [comment](https://github.com/paritytech/polkadot-sdk/pull/4518#issuecomment-2134731355) - [ ] Backport to `[email protected]` release, so we can use it for next fellows release: https://github.com/polkadot-fellows/runtimes/pull/324 - [ ] Backport to `[email protected]` release --------- Co-authored-by:Branislav Kontur <[email protected]>