Update dependencies.

Author: prochnowc

Directory.Build.props

@@ -14,6 +14,7 @@
     <RestorePackagesWithLockFile>true</RestorePackagesWithLockFile>
     <RestoreLockedMode Condition="'$(CI)' == 'true'">true</RestoreLockedMode>
     -->
+    <DefineConstants>$(DefineConstants);ENABLE_NULLABLE</DefineConstants>
   </PropertyGroup>
 
   <Import Project="./build/shared/dotnet/common.props" />

build/dependency-versions.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
     <Microsoft_Extensions_Version>3.1.0</Microsoft_Extensions_Version>
-    <AppCore_Shared_Version>0.4.0-alpha.*</AppCore_Shared_Version>
+    <AppCore_Shared_Version>0.4.3</AppCore_Shared_Version>
   </PropertyGroup>
 </Project>