Maintenance: Bump telephone_number from 1.4.14 to 1.4.15

Bumps [telephone_number](https://github.com/mobi/telephone_number) from 1.4.14 to 1.4.15.
- [Release notes](https://github.com/mobi/telephone_number/releases)
- [Changelog](https://github.com/mobi/telephone_number/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mobi/telephone_number/compare/v1.4.14...v1.4.15)

Gemfile.lock

@@ -545,7 +545,7 @@ GEM
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
     tcr (0.2.2)
-    telephone_number (1.4.14)
+    telephone_number (1.4.15)
     test-unit (3.5.3)
       power_assert
     thor (1.2.1)