Target net8 so we can use the latest version of Npgsql

Author: droyad

src/dbup-postgresql/dbup-postgresql.csproj

@@ -6,7 +6,7 @@
     <Company>DbUp Contributors</Company>
     <Product>DbUp</Product>
     <Copyright>Copyright © DbUp Contributors 2015</Copyright>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <AssemblyName>dbup-postgresql</AssemblyName>
     <RootNamespace>DbUp.Postgresql</RootNamespace>
     <PackageId>dbup-postgresql</PackageId>
@@ -24,7 +24,7 @@
 
   <ItemGroup>
     <PackageReference Include="dbup-core" Version="6.0.4" />
-    <PackageReference Include="Npgsql" Version="8.0.3" />
+    <PackageReference Include="Npgsql" Version="9.0.2" />
   </ItemGroup>
 
   <ItemGroup>