feat: Prepare next release cycle (4.9.0) (#1561)

Author: HofmeisterAn

Directory.Build.props

@@ -2,7 +2,7 @@
 <Project>
   <PropertyGroup>
     <PackageId>$(AssemblyName)</PackageId>
-    <Version>4.8.1</Version>
+    <Version>4.9.0</Version>
     <AssemblyVersion>$(Version)</AssemblyVersion>
     <FileVersion>$(Version)</FileVersion>
     <Product>Testcontainers</Product>