Relax JSON schema and update deps (#19)

Co-authored-by: Smaug123 <3138005+Smaug123@users.noreply.github.com>
Reviewed-on: #19

PureGym/Dto.fs

@@ -187,8 +187,7 @@ type GymAttendance =
         [<JsonRequired>]
         TotalPeopleInGym : int
         /// How many people are in classes at the gym as of this statistics snapshot
-        [<JsonRequired>]
-        TotalPeopleInClasses : int
+        TotalPeopleInClasses : int option
         /// E.g. " or fewer"
         TotalPeopleSuffix : string option
         /// Whether the number of people in the gym is approximate. This appears to become true when the number
@@ -219,10 +218,10 @@ type GymAttendance =
                 $" out of %i{this.MaximumCapacity} maximum"
 
         let classes =
-            if this.TotalPeopleInClasses = 0 then
-                ""
-            else
-                $"\n%i{this.TotalPeopleInClasses} in classes"
+            match this.TotalPeopleInClasses with
+            | None
+            | Some 0 -> ""
+            | Some totalPeopleInClasses -> $"\n%i{totalPeopleInClasses} in classes"
 
         $"""%i{this.TotalPeopleInGym}%s{totalPeopleSuffix} in gym%s{capacity} (is exact: %c{Char.emoji (not this.IsApproximate)})%s{classes}
 Query made at %s{this.AttendanceTime.ToString "s"}%s{this.AttendanceTime.ToString "zzz"}