remove unnesseccery variable

Pilz.IO/FileLocker.cs

@@ -41,7 +41,7 @@ namespace Pilz.IO
                             var fs = new FileStream(lockFile, FileMode.Open, FileAccess.Read);
                             fs.Close();
                         }
-                        catch (IOException ex)
+                        catch (IOException)
                         {
                             isLocked = true;
                         }