Bump xo from 0.50.0 to 0.51.0 (#309)

Bumps [xo](https://github.com/xojs/xo) from 0.50.0 to 0.51.0.
- [Release notes](https://github.com/xojs/xo/releases)
- [Commits](xojs/xo@v0.50.0...v0.51.0)

---
updated-dependencies:
- dependency-name: xo
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

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

package.json

@@ -52,7 +52,7 @@
     "ava": "^4.3.1",
     "execa": "^6.1.0",
     "test-rule-package": "./test/custom-rules/test-rule-package",
-    "xo": "^0.50.0"
+    "xo": "^0.51.0"
   },
   "xo": {
     "prettier": true,