Fix typo

Author: alex268

auth-providers/oauth2-provider/src/main/java/tech/ydb/auth/OAuth2TokenExchangeProvider.java

@@ -276,7 +276,7 @@ private List<NameValuePair> fixedArgs() {
             List<NameValuePair> params = new ArrayList<>();
 
             // Required parameters
-            params.add(new BasicNameValuePair("grand_type", grantType));
+            params.add(new BasicNameValuePair("grant_type", grantType));
             params.add(new BasicNameValuePair("requested_token_type", requestedTokenType));
 
             // Optional parameters