Bump prettier from 1.18.2 to 2.2.1 (#318)

Bumps [prettier](https://github.com/prettier/prettier) from 1.18.2 to 2.2.1.
- [Release notes](https://github.com/prettier/prettier/releases)
- [Changelog](https://github.com/prettier/prettier/blob/main/CHANGELOG.md)
- [Commits](prettier/prettier@1.18.2...2.2.1)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Dudley Carr <dudley.carr@gmail.com>

package.json

@@ -43,7 +43,7 @@
     "eslint": "^6.1.0",
     "mocha": "^5.2.0",
     "nock": "^10.0.6",
-    "prettier": "^1.18.2",
+    "prettier": "^2.2.1",
     "should": "^13.2.3",
     "sinon": "~7.4.1",
     "temp": "^0.8.0"