fix generating captcha in PHP with workaround

* allows php8 working too
* bcit-ci/CodeIgniter#6256

appsys/helpers/captcha_helper.php

@@ -278,12 +278,12 @@ function create_captcha($data = '', $img_path = '', $img_url = '', $font_path =
 		{
 			$theta += $thetac;
 			$rad = $radius * ($i / $points);
-			$x = ($rad * cos($theta)) + $x_axis;
-			$y = ($rad * sin($theta)) + $y_axis;
+			$x = round(($rad * cos($theta)) + $x_axis);
+			$y = round(($rad * sin($theta)) + $y_axis);
 			$theta += $thetac;
 			$rad1 = $radius * (($i + 1) / $points);
-			$x1 = ($rad1 * cos($theta)) + $x_axis;
-			$y1 = ($rad1 * sin($theta)) + $y_axis;
+			$x1 = round(($rad1 * cos($theta)) + $x_axis);
+			$y1 = round(($rad1 * sin($theta)) + $y_axis);
 			imageline($im, $x, $y, $x1, $y1, $colors['grid']);
 			$theta -= $thetac;
 		}