Makes extension check case insensitive

src/main/java/net/knarcraft/ffmpegconverter/utility/FileUtil.java

@@ -52,7 +52,7 @@ public final class FileUtil {
         }
         //Get a list of all files which are folders and has one of the extensions specified
         File[] foundFiles = folder.listFiles((file) -> file.isFile() &&
-                ListUtil.listContains(extensions, (item) -> file.getName().endsWith(item)));
+                ListUtil.listContains(extensions, (item) -> file.getName().toLowerCase().endsWith(item)));
         //Return if recursion is finished
         if (maxRecursions == 1) {
             return foundFiles;