Tag cog crashes bot on systems with non utf8 default encoding.
The tag cog leaves out encoding when opening files, assuming the default is UTF8  but that is not the case on some OSs and fails with the `UnicodeDecodeError`.

The offending block of code can be found here:
https://github.com/python-discord/bot/blob/7571cabe65e39d231523e713923cd23b927225bc/bot/cogs/tags.py#L43-L48

paging @kmonteith25 here as they mentioned the issue in #dev-contrib
diff --git a/bot/cogs/tags.py b/bot/cogs/tags.py
index 9ba33d7e..a813ffff 100644
--- a/bot/cogs/tags.py
+++ b/bot/cogs/tags.py
@@ -43,7 +43,7 @@ class Tags(Cog):
             tag = {
                 "title": tag_title,
                 "embed": {
-                    "description": file.read_text()
+                    "description": file.read_text(encoding="utf-8")
                 }
             }
             cache[tag_title] = tag
['bot/cogs/tags.py']