build(deps): bump orml-xtokens from b3694e6 to 2778a86 (#3020)

Bumps [orml-xtokens](https://github.com/open-web3-stack/open-runtime-module-library) from `b3694e6` to `2778a86`.
- [Release notes](https://github.com/open-web3-stack/open-runtime-module-library/releases)
- [Commits](open-web3-stack/open-runtime-module-library@b3694e6...2778a86)

---
updated-dependencies:
- dependency-name: orml-xtokens
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Kai <[email protected]>