remove type restriction callable

The type check `is_callable()` returns true but the type hint throws
when the method is not static.

.travis.yml

@@ -20,6 +20,7 @@ before_script:
   - composer install --no-interaction
   - sh -c 'if [ "$TRAVIS_PHP_VERSION" = "7.1" ]; then composer require satooshi/php-coveralls:~0.6@stable; fi;'
   - mkdir -p build/logs
+
 script:
   - composer code-style
   - bin/phpunit -c phpunit.xml --color=always --coverage-clover=build/logs/clover.xml --coverage-text

riki-dev/app/Http/HttpKernel.php

@@ -172,7 +172,7 @@ protected static function collectRoutes(MiddlewareRouteCollector $router)
      * @param callable $callable
      * @return bool
      */
-    protected function isStatic(callable $callable): bool
+    protected function isStatic($callable): bool
     {
         if (is_array($callable)) {
             list($class, $method) = $callable;

skeleton/routing/app/Http/Controller/AbstractController.php

@@ -4,7 +4,6 @@
 
 use App\Application;
 use function GuzzleHttp\Psr7\stream_for;
-use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Tal\ServerResponse;
 

skeleton/routing/app/Http/HttpKernel.php

@@ -172,7 +172,7 @@ protected static function collectRoutes(MiddlewareRouteCollector $router)
      * @param callable $callable
      * @return bool
      */
-    protected function isStatic(callable $callable): bool
+    protected function isStatic($callable): bool
     {
         if (is_array($callable)) {
             list($class, $method) = $callable;