Fix Instagram OAuth URL formatting and scope separator (#1435)

Co-authored-by: atymic <atymicq@gmail.com>

Author: Faisd405

src/Instagram/Provider.php

@@ -10,7 +10,7 @@ class Provider extends AbstractProvider
 {
     public const IDENTIFIER = 'INSTAGRAM';
 
-    protected $scopeSeparator = ' ';
+    protected $scopeSeparator = ',';
 
     /**
      * The user fields being requested.
@@ -21,6 +21,18 @@ class Provider extends AbstractProvider
 
     protected $scopes = ['instagram_business_basic'];
 
+    protected function buildAuthUrlFromBase($url, $state)
+    {
+        $query = http_build_query(
+            $this->getCodeFields($state),
+            '',
+            '&',
+            $this->encodingType
+        );
+
+        return $url . '?' . urldecode($query);
+    }
+
     protected function getAuthUrl($state): string
     {
         return $this->buildAuthUrlFromBase('https://api.instagram.com/oauth/authorize', $state);