Minor fixups in linkbot on the most recent changes for HTML decoding

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

plugins/linkbot.py

@@ -37,11 +37,13 @@ class TitleParser(HTMLParser):
         if tag == "title":
             self.parsing_title = True
         elif tag == "meta":
-            attrs = dict(attrs_list)
-            if attrs.get("property", None) == "og:title":
-                self.parsed_title = attrs.get("content", None)
-            elif attrs.get("name", None) == "title":
-                self.parsed_title = attrs.get("content", None)
+            # filter None values
+            attrs = {name: value for name, value in attrs_list if value}
+            # where property="og:title" or name="title", use the "content" attribute
+            if attrs.get("property", None) == "og:title" and "content" in attrs:
+                self.parsed_title = html.unescape(attrs["content"])
+            elif attrs.get("name", None) == "title" and "content" in attrs:
+                self.parsed_title = html.unescape(attrs["content"])
 
     def handle_endtag(self, tag: str) -> None:
         match tag.lower():