Update email service to handle single-player tournament inscription

tournaments/services/email_service.py

@@ -113,11 +113,18 @@ class TournamentEmailService:
         link_text = f"informations sur {tournament_prefix_that}{tournament_word}"
         absolute_url = f'<a href="{absolute_url}">{link_text}</a>'
 
-        body_parts.extend([
-            f"\nDate d'inscription: {inscription_date}",
-            f"\nÉquipe inscrite: {captain.name()} et {other_player.name()}",
-            f"\nVoir les {absolute_url}"
-        ])
+        if other_player:
+            body_parts.extend([
+                f"\nDate d'inscription: {inscription_date}",
+                f"\nÉquipe inscrite: {captain.name()} et {other_player.name()}",
+                f"\nVoir les {absolute_url}"
+            ])
+        else:
+            body_parts.extend([
+                f"\nDate d'inscription: {inscription_date}",
+                f"\nVotre inscription: {captain.name()}",
+                f"\nVoir les {absolute_url}"
+            ])
 
         # Add payment information if applicable
         if tournament.should_request_payment():