deps: bump @multiformats/mafmt from 11.1.2 to 12.0.0 (libp2p#257)

Bumps [@multiformats/mafmt](https://github.com/multiformats/js-mafmt) from 11.1.2 to 12.0.0.
- [Release notes](https://github.com/multiformats/js-mafmt/releases)
- [Changelog](https://github.com/multiformats/js-mafmt/blob/master/CHANGELOG.md)
- [Commits](multiformats/js-mafmt@v11.1.2...v12.0.0)

---
updated-dependencies:
- dependency-name: "@multiformats/mafmt"
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

package.json

@@ -147,7 +147,7 @@
     "@libp2p/interfaces": "^3.2.0",
     "@libp2p/logger": "^2.0.0",
     "@libp2p/utils": "^3.0.2",
-    "@multiformats/mafmt": "^11.0.3",
+    "@multiformats/mafmt": "^12.0.0",
     "@multiformats/multiaddr": "^12.0.0",
     "stream-to-it": "^0.2.2"
   },