Show assembly version

This PR fixes a long-standing issue where the reported version number is just the tag with a `-` prefix.

This was caused by the logic dropping the assembly version number if a tag exists, but prefixing it with a dash.

The fix is to now show both the assembly version and the tag.

Duplicati/License/VersionNumbers.cs

@@ -57,7 +57,7 @@ namespace Duplicati.License
 
             var v = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
             if (!string.IsNullOrWhiteSpace(TAG))
-                v = " - " + TAG;
+                v += " - " + TAG;
 #if DEBUG
             v = " - debug";
 #endif