修复ImgUtil.convert png转jpg在jdk9+中失败问题

hutool-core/src/test/java/cn/hutool/core/img/IssueI8L8UATest.java

@@ -0,0 +1,15 @@
+package cn.hutool.core.img;
+
+import cn.hutool.core.io.FileUtil;
+import org.junit.Ignore;
+import org.junit.Test;
+
+public class IssueI8L8UATest {
+	@Test
+	@Ignore
+	public void convertTest() {
+		ImgUtil.convert(
+			FileUtil.file("d:/test/1.png"),
+			FileUtil.file("d:/test/1.jpg"));
+	}
+}