fix(HtmlParser): remove trailing line breaks

Some fediverse servers (e.g. lemmy) add a trailing line break to the
content. Since we add them as well, this can cause up to three line
breaks at the end of a post, resulting in a blank space.
This removes the trailing line breaks before parsing the content.

mastodon/src/main/java/org/joinmastodon/android/ui/text/HtmlParser.java

@@ -123,6 +123,9 @@ public SpanInfo(Object span, int start, Element element, boolean more){
 		int colorInsert=UiUtils.getThemeColor(context, R.attr.colorM3Success);
 		int colorDelete=UiUtils.getThemeColor(context, R.attr.colorM3Error);
 
+		if(source.endsWith("\n"))
+			source=source.stripTrailing();
+
 		Jsoup.parseBodyFragment(source).body().traverse(new NodeVisitor(){
 			private final ArrayList<SpanInfo> openSpans=new ArrayList<>();