Instructions to import/update nikic/fast-route

1. Update any dependencies
2. Confirm compatible versions with Slim Framework
2. Download and unzip the latest release from https://github.com/nikic/fast-route
3. Remove the following files/folders:
  - `test` directory
  - `.gitignore`
  - `.httconfig`
  - `.travis.yml`
  - `psalm.xml`
  - `FastRoute.hhi`
3. Replace the files in fast-route/* with those prepared
