Merge pull request #227 from fsprojects/prefer-dispose-over-asyncdispose

Prefer `IDisposable` over `IAsyncDisposable` for disposing `ReaderWriterLock`

Author: abelbraaksma

src/FSharp.Control.TaskSeq/TaskSeqInternal.fs

@@ -978,13 +978,11 @@ module internal TaskSeqInternal =
                 go <- step
         }
 
-        interface IAsyncDisposable with
-            override _.DisposeAsync() =
+        interface IDisposable with
+            override _.Dispose() =
                 if not (isNull _rwLock) then
                     _rwLock.Dispose()
 
-                ValueTask.CompletedTask
-
     let except itemsToExclude (source: TaskSeq<_>) =
         checkNonNull (nameof source) source
         checkNonNull (nameof itemsToExclude) itemsToExclude