Fsdk: fix build

Somehow, the 'macOS--dotnet6-and-mono' and
'linux-*-github--dotnet-*' CI lanes started
failing this compiler error:

```
/home/runner/work/fsx/fsx/Fsdk/Process.fs(22,31): error FS0041: No overloads match for method 'Read'.

Known type of argument: int ref

Available overloads:
 - Volatile.Read(location: inref<bool>) : bool // Argument 'location' doesn't match
 - Volatile.Read(location: inref<byte>) : byte // Argument 'location' doesn't match
 - Volatile.Read(location: inref<float32>) : float32 // Argument 'location' doesn't match
 - Volatile.Read(location: inref<float>) : float // Argument 'location' doesn't match
 - Volatile.Read(location: inref<int16>) : int16 // Argument 'location' doesn't match
 - Volatile.Read(location: inref<int64>) : int64 // Argument 'location' doesn't match
 - Volatile.Read(location: inref<int>) : int // Argument 'location' doesn't match
 - Volatile.Read(location: inref<nativeint>) : nativeint // Argument 'location' doesn't match
 - Volatile.Read(location: inref<sbyte>) : sbyte // Argument 'location' doesn't match
 - Volatile.Read(location: inref<uint16>) : uint16 // Argument 'location' doesn't match
 - Volatile.Read(location: inref<uint32>) : uint32 // Argument 'location' doesn't match
 - Volatile.Read(location: inref<uint64>) : uint64 // Argument 'location' doesn't match
 - Volatile.Read(location: inref<unativeint>) : unativeint // Argument 'location' doesn't match
 - Volatile.Read<'T when 'T: not struct>(location: inref<'T>) : 'T // Argument 'location' doesn't match
```

Which makes me think that they are upgrading to newer
.NET versions instead of being pinned...

The build fix works but not sure it's correct at runtime
TBH. We will see when we start using the new version of
Fsdk nuget package soon...

Fsdk/Process.fs

@@ -19,7 +19,7 @@ module Process =
             let myTicket = Interlocked.Increment ticketsCount
             Monitor.Enter innerLock
 
-            while myTicket <> Volatile.Read ticketToRide do
+            while myTicket <> ticketToRide.Value do
                 Monitor.Wait innerLock |> ignore
 
         member __.Exit() =