build(deps-dev): bump coveralls from 3.1.0 to 3.1.1

Bumps [coveralls](https://github.com/nickmerwin/node-coveralls) from 3.1.0 to 3.1.1.
- [Release notes](https://github.com/nickmerwin/node-coveralls/releases)
- [Commits](nickmerwin/node-coveralls@v3.1.0...3.1.1)

---
updated-dependencies:
- dependency-name: coveralls
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -25,7 +25,7 @@
   "homepage": "https://github.com/alvarocastro/backoff#readme",
   "devDependencies": {
     "ava": "3.15.0",
-    "coveralls": "3.1.0",
+    "coveralls": "3.1.1",
     "nyc": "15.1.0",
     "semantic-release": "^17.1.2",
     "xo": "0.39.1"