fix: cast integer values to string before rawurlencode in query string builder

[vincentmary]

Fix rawurlencode() type error on integer query parameters

Fixes #34

Problem

When building a query string, integer values were passed directly to rawurlencode(), which expects a string. This caused a fatal error:

rawurlencode(): Argument #1 ($string) must be of type string, int given
For example, GetTransactionHistoryQueryParams defines startDate and endDate as int (Unix timestamps). Passing them to getQueryString() triggered the error:

  $params = new GetTransactionHistoryQueryParams();
  $params->startDate = 1700000000;
  $params->endDate   = 1710000000;

  $params->getQueryString(); // ❌ Fatal error: rawurlencode() expects string, int given

Solution

Added an explicit is_int check in AbstractRequestQueryParams::getQueryString() so integer values are appended directly without going through rawurlencode(), consistent with how booleans are already handled.

  } elseif (is_int($value)) {
      $queryStringParams[] = $propName . '=' . $value;
  }

Changes

• src/RequestQueryParams/AbstractRequestQueryParams.php — added elseif (is_int($value)) branch to handle integer query parameters safely

[pkotets]

Thanks a lot for the fix, and especially for the test!
Adding test coverage for this library is still on my to-do list... :)