Update Program.cs

Author: SimonCropp

src/DiffEngineWord/Program.cs

@@ -1,3 +1,5 @@
+using System.Runtime.InteropServices;
+
 static partial class Program
 {
     static int Main(string[] args)
@@ -75,6 +77,10 @@ static int Main(string[] args)
         using var process = Process.GetProcessById(processId);
         process.WaitForExit();
 
+        // Release COM objects
+        Marshal.ReleaseComObject(comparedDoc);
+        Marshal.ReleaseComObject(word);
+
         return 0;
     }