change version to 1.49.3-beta

Author: oldrev

GeographicLib/Directory.Build.props

@@ -5,6 +5,7 @@
     <Title>This is an attempt to port the Java version of GeographicLib to C#.</Title>
     <PackageTags>geographic;gis;geodesic;gnomonic;</PackageTags>
     <VersionPrefix>1.49.3</VersionPrefix>
+    <VersionSuffix>beta</VersionSuffix>
   </PropertyGroup>
 
   <Import Project="../Shared.props" />