Bump Npgsql from 4.0.3 to 6.0.2

Bumps [Npgsql](https://github.com/npgsql/npgsql) from 4.0.3 to 6.0.2.
- [Release notes](https://github.com/npgsql/npgsql/releases)
- [Commits](npgsql/npgsql@v4.0.3...v6.0.2)

---
updated-dependencies:
- dependency-name: Npgsql
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/NHibernate.Test/NHibernate.Test.csproj

@@ -64,7 +64,7 @@
     <PackageReference Include="NUnit3TestAdapter" Version="3.15.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.4" />
     <PackageReference Include="FirebirdSql.Data.FirebirdClient" Version="6.6.0" />
-    <PackageReference Include="Npgsql" Version="4.0.3" />
+    <PackageReference Include="Npgsql" Version="6.0.2" />
     <PackageReference Include="MySql.Data" Version="8.0.25" />
   </ItemGroup>
   <ItemGroup Condition="$(NhNetFx)">