Bump laravel/framework from 5.4.32 to 5.5.50

Bumps [laravel/framework](https://github.com/laravel/framework) from 5.4.32 to 5.5.50.
- [Release notes](https://github.com/laravel/framework/releases)
- [Changelog](https://github.com/laravel/framework/blob/10.x/CHANGELOG.md)
- [Commits](laravel/framework@v5.4.32...v5.5.50)

---
updated-dependencies:
- dependency-name: laravel/framework
  dependency-type: direct:production
...

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

composer.json

@@ -6,7 +6,7 @@
     "type": "project",
     "require": {
         "php": ">=5.6.4",
-        "laravel/framework": "5.4.*",
+        "laravel/framework": "5.5.*",
         "laravel/tinker": "~1.0"
     },
     "require-dev": {