refactor(auth): clear oauth state after validation

Author: xHeaven

packages/auth/src/OAuth/GenericOAuthClient.php

@@ -100,7 +100,12 @@ public function fetchUser(AccessToken $token): OAuthUser
 
     public function authenticate(Request $request, Closure $map): Authenticatable
     {
-        if ($this->session->get($this->sessionKey) !== $request->get('state')) {
+        $expectedState = $this->session->get($this->sessionKey);
+        $actualState = $request->get('state');
+
+        $this->session->remove($this->sessionKey);
+
+        if ($expectedState !== $actualState) {
             throw new OAuthStateWasInvalid();
         }