chore(deps): bump polkadot-sdk from b2bcb74 to 3bfc6ec

Bumps [polkadot-sdk](https://github.com/paritytech/polkadot-sdk) from `b2bcb74` to `3bfc6ec`.
- [Release notes](https://github.com/paritytech/polkadot-sdk/releases)
- [Commits](paritytech/polkadot-sdk@b2bcb74...3bfc6ec)

---
updated-dependencies:
- dependency-name: polkadot-sdk
  dependency-version: 3bfc6ec36a4d5ad6e362d8fe821cdbbc21621e3c
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]