Upgrade solution to .NET 8.0 LTS

[Copilot]

The solution was on .NET Core 3.1 (EOL December 2022) and netstandard2.0. Upgraded to .NET 8.0 LTS (supported until November 2026).

Changes

• Library projects (9 projects): netstandard2.0 → net8.0

  • FluentEmail.Core, FluentEmail.Razor, FluentEmail.Liquid
  • FluentEmail.Smtp, FluentEmail.SendGrid, FluentEmail.Mailtrap, FluentEmail.MailKit, FluentEmail.Mailgun, FluentEmail.Graph

• Test projects (3 projects): netcoreapp3.1 → net8.0

  • FluentEmail.Core.Tests, FluentEmail.Razor.Tests, FluentEmail.Liquid.Tests

• Test framework packages: Updated to latest .NET 8.0-compatible versions

  • Microsoft.NET.Test.Sdk: 16.6.1 → 17.12.0
  • NUnit: 3.12.0/3.13.0 → 3.14.0 (staying on v3 to avoid breaking API changes in v4)
  • NUnit3TestAdapter: 3.16.1/3.17.0 → 4.6.0
  • Microsoft.Extensions.FileProviders.Physical: 5.0.0 → 8.0.0

• Removed duplicate package references: Consolidated test dependencies in test/Directory.Build.props

Notes

All projects now target a single framework version (net8.0) rather than multi-targeting. This simplifies the build and aligns with the library's distribution model.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• api.mailgun.net
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/FluentEmail.Core.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/FluentEmail.Core.Tests.deps.json /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/testhost.dll --port 33157 --endpoint 127.0.0.1:033157 --role client --parentprocessid 4866 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/FluentEmail.Core.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/FluentEmail.Core.Tests.deps.json /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/testhost.dll --port 45303 --endpoint 127.0.0.1:045303 --role client --parentprocessid 5127 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/FluentEmail.Core.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/FluentEmail.Core.Tests.deps.json /home/REDACTED/work/FluentEmail/FluentEmail/test/FluentEmail.Core.Tests/bin/Debug/net8.0/testhost.dll --port 38037 --endpoint 127.0.0.1:038037 --role client --parentprocessid 5254 --telemetryoptedin false (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

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This section details on the original issue you should resolve

<issue_title>upgrade entire solution to use the latest version of .net</issue_title>
<issue_description>I inherited this repository. It hasn;t been touched in a few years before I got it, and I want to upgrade it to the latest version of .net possible.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes upgrade entire solution to use the latest version of .net #12

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[steve-kaschimer]

LooksGood