docker files fixes from liaqat

src/Managing.Core/DateHelpers.cs

@@ -0,0 +1,10 @@
+namespace Managing.Core;
+
+public class DateHelpers
+{
+    public static DateTime GetFromUnixTimestamp(int unixTimestamp)
+    {
+        var dat_Time = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Local);
+        return dat_Time.AddSeconds(unixTimestamp);
+    }
+}