Fix warning in tests

@@ -2,6 +2,7 @@
 
 ## 1.3.24
 
+- Fix warning in tests
 - Fix warning in example
 - Format Java code
 

@@ -213,7 +213,7 @@ void main() {
                       child: UrlLink(
                           child: Text(
                             'https://github.com/DavBfr/dart_pdf/',
-                            style: TextStyle(
+                            style: const TextStyle(
                               color: PdfColors.grey,
                               fontSize: 8,
                               decoration: TextDecoration.underline,

@@ -147,7 +147,7 @@ void main() {
                 para,
                 style: TextStyle(
                   font: ttf,
-                  background: BoxDecoration(color: PdfColors.purple50),
+                  background: const BoxDecoration(color: PdfColors.purple50),
                 ),
               ),
             ]));