Use "speaker" tag for detecting speakers

Author: marcoacierno

backend/badges/roles.py

@@ -142,7 +142,7 @@ def _calculate_roles(
         if "sponsor" in tags:
             roles.append(Role.SPONSOR)
 
-        if "speakers" in tags:
+        if "speakers" in tags or "speaker" in tags:
             roles.append(Role.SPEAKER)
 
     # We do not know if they are a speaker via voucher code

badge-service/main.js

@@ -10,7 +10,7 @@ const EMPTY_BADGES_COUNT = {
   SPEAKER: 25,
   STAFF: 20,
   SPONSOR: 30,
-  KEYNOTER: 5,
+  KEYNOTER: 6,
   DJANGO_GIRLS: 25,
 };