fix mangajar pages issue (#5945)

src/en/mangajar/build.gradle

@@ -5,7 +5,7 @@ ext {
     extName = 'MangaJar'
     pkgNameSuffix = 'en.mangajar'
     extClass = '.MangaJar'
-    extVersionCode = 2
+    extVersionCode = 3
     libVersion = '1.2'
 }
 

src/en/mangajar/src/eu/kanade/tachiyomi/extension/en/mangajar/MangaJar.kt

@@ -143,7 +143,7 @@ class MangaJar : ParsedHttpSource() {
 
     override fun pageListParse(document: Document): List<Page> {
         return document.select("img[data-page]").mapIndexed { i, element ->
-            Page(i, "", element.attr("src"))
+            Page(i, "", element.attr("data-alternative"))
         }
     }