Mangadex markdown cleanup removes --- only with newline (#7282)

* Update MangaDexHelper.kt

* Update build.gradle

* Update build.gradle

src/all/mangadex/build.gradle

@@ -1,7 +1,7 @@
 ext {
     extName = 'MangaDex'
     extClass = '.MangaDexFactory'
-    extVersionCode = 198
+    extVersionCode = 199
     isNsfw = true
 }
 

src/all/mangadex/src/eu/kanade/tachiyomi/extension/all/mangadex/MangaDexHelper.kt

@@ -156,7 +156,7 @@ class MangaDexHelper(lang: String) {
      */
     private fun String.removeEntitiesAndMarkdown(): String {
         return removeEntities()
-            .substringBefore("---")
+            .substringBefore("\n---")
             .replace(markdownLinksRegex, "$1")
             .replace(markdownItalicBoldRegex, "$1")
             .replace(markdownItalicRegex, "$1")