Bump Npgsql from 6.0.2 to 6.0.4

Bumps [Npgsql](https://github.com/npgsql/npgsql) from 6.0.2 to 6.0.4.
- [Release notes](https://github.com/npgsql/npgsql/releases)
- [Commits](npgsql/npgsql@v6.0.2...v6.0.4)

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

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

test/FluentCommand.PostgreSQL.Tests/FluentCommand.PostgreSQL.Tests.csproj

@@ -21,7 +21,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
     <PackageReference Include="dbup-postgresql" Version="4.5.0" />
-    <PackageReference Include="Npgsql" Version="6.0.2" />
+    <PackageReference Include="Npgsql" Version="6.0.4" />
     <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="6.0.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="6.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.0.0" />