add comma as disallowed char at end of url

Do not include comma as part of a URL if it is followed by whitespace.
This allows users to make lists of URLs.

Closes: https://github.com/damus-io/damus/issues/1833

LNURL1DP68GURN8GHJ7EM9W3SKCCNE9E3K7MF0D3H82UNVWQHKWUN9V4HXGCTHDC6RZVGR8SW3G

Signed-off-by: kernelkind <kernelkind@gmail.com>
Signed-off-by: William Casarin <jb55@jb55.com>

damus-c/cursor.h

@@ -498,7 +498,7 @@ static inline int next_char_is_whitespace(unsigned char *curChar, unsigned char
 }
 
 static int char_disallowed_at_end_url(char c){
-    return c == '.';
+    return c == '.' || c == ',';
 }
 
 static inline int is_final_url_char(unsigned char *curChar, unsigned char *endChar){