Update SDK to .NET 8 target net6.0 and net8.0, drop netcoreapp3.1, fix tests culture assert issues #490

	name: Build
	on:
	pull_request:
	workflow_dispatch:
	push:
	branches:
	- main
	jobs:
	build:
	name: Build
	runs-on: ${{ matrix.os }}
	strategy:
	fail-fast: false
	matrix:
	# libsass.dylib is not working on macos-14
	os: [windows-latest, ubuntu-latest, macos-13]
	env:
	# https://github.com/NuGet/Home/issues/11548
	# https://twitter.com/xoofx/status/1488617114940452872?s=20&t=BKSN4j9rP6fOyg8l7aW0eg
	NUGET_CERT_REVOCATION_MODE: offline
	steps:
	- name: Get Source
	uses: actions/checkout@v4
	with:
	submodules: recursive
	- name: Install .NET Core SDK
	uses: actions/setup-dotnet@v4
	with:
	dotnet-version: \|
	3.1.x
	6.0.x
	8.0.x
	- name: Build and Test
	run: dotnet test --logger "trx;LogFileName=test-results.trx"
	- name: Upload Test Results
	uses: actions/upload-artifact@v4
	if: success() \|\| failure()
	with:
	name: test-results-${{ matrix.os }}
	path: '**/test-results.trx'

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