Fix wrong regex when channel id is at the end of the url

It had no "&" at the end.

Author: Stypox

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeChannelInfoItemExtractor.java

@@ -59,7 +59,7 @@ public String getUrl() throws ParsingException {
         String buttonTrackingUrl = el.select("button[class*=\"yt-uix-button\"]").first()
                 .attr("abs:data-href");
 
-        Pattern channelIdPattern = Pattern.compile("(?:.*?)\\%252Fchannel\\%252F(.+?)\\%26(?:.*)");
+        Pattern channelIdPattern = Pattern.compile("(?:.*?)\\%252Fchannel\\%252F([A-Za-z0-9\\-\\_]+)(?:.*)");
         Matcher match = channelIdPattern.matcher(buttonTrackingUrl);
 
         if (match.matches()) {