Escape backslashes in invite regex

Author: ChrisLovering

pydis_core/utils/regex.py

@@ -3,7 +3,7 @@
 import re
 
 DISCORD_INVITE = re.compile(
-    r"(https?://)?(www\.)?"                      # Optional http(s) and www.
+    r"(https?:\/\/)?(www\.)?"                      # Optional http(s) and www.
     r"(discord(app)?)?"                          # Optional discord(app)
     r"([.,]|dot)"                                # Various characters to cover dots
     r"("