Don't add a file:// prefix to URI that already have a scheme (jsonrainbow#455)

Some URI types do not pass validation against \FILTER_VAR_URL (e.g.
phar://), but are still valid and still have a scheme. This patch
catches those situations via a simple regex.

Author: erayd

src/JsonSchema/Uri/UriResolver.php

@@ -77,7 +77,11 @@ public function generate(array $components)
     public function resolve($uri, $baseUri = null)
     {
         // treat non-uri base as local file path
-        if (!is_null($baseUri) && !filter_var($baseUri, \FILTER_VALIDATE_URL)) {
+        if (
+            !is_null($baseUri) &&
+            !filter_var($baseUri, \FILTER_VALIDATE_URL) &&
+            !preg_match('|^[^/]+://|u', $baseUri)
+        ) {
             if (is_file($baseUri)) {
                 $baseUri = 'file://' . realpath($baseUri);
             } elseif (is_dir($baseUri)) {