fix: correct syntax for null coalescing in group permissions selection

Author: https-richardy

Applications/Backend/Source/HttpsRichardy.Federation.Infrastructure/Security/JwtSecurityTokenService.cs

@@ -22,7 +22,7 @@ public async Task<Result<SecurityToken>> GenerateAccessTokenAsync(User user, Can
             .Where(group => user.Groups.Any(userGroup => userGroup.Id == group.Id))
             .ToList();
 
-        var groupPermissions = groups.SelectMany(group => group.Permissions ?? [  ]);
+        var groupPermissions = groups.SelectMany(group => group.Permissions ?? []);
         var permissions = user.Permissions
             .Concat(groupPermissions)
             .GroupBy(permission => permission.Name)