Try to get the template integration tests working by making them use the 8.0.0 alpha build

Instead of pulling the 6.1.X build off NuGet.org.
This might bootstrap the tests enough to get them all passing

Author: Numpsy

src/app/fake-cli/fake-cli.fsproj

@@ -3,7 +3,7 @@
         <PackAsTool>true</PackAsTool>
         <OutputType>Exe</OutputType>
         <ToolCommandName>fake</ToolCommandName>
-        <TargetFrameworks>net8.0;net6.0</TargetFrameworks>
+        <TargetFramework>net8.0</TargetFramework>
         <RollForward>Major</RollForward>
         <RuntimeIdentifiers>linux-x64</RuntimeIdentifiers>
         <!-- Debian packaging -->

src/template/fake-template/Content/.config/dotnet-tools.json

@@ -4,7 +4,7 @@
   "tools": {
     "fake-cli": {
 //#if (version == "latest")
-      "version": "6.1.3",
+      "version": "8.0.0-alpha",
 ////#else
       //"version": "(version)",
 //#endif
@@ -13,4 +13,4 @@
       ]
     }
   }
-}
+}

src/test/Fake.DotNet.Cli.IntegrationTests/TemplateTests.fs

@@ -69,10 +69,32 @@ let isProcessSucceeded message (r: ProcessResult<ProcessOutput>) =
 
 let timeout = (TimeSpan.FromMinutes 10.)
 
+let writeTestNuGetConfig rootDir =
+
+    let nugetConfigFilePath = System.IO.Path.Combine(rootDir, "NuGet.config")
+
+    let nugetPackageFolder =
+        System.IO.Path.Combine(__SOURCE_DIRECTORY__, "..", "..", "..", "release", "dotnetcore")
+
+    let nugetConfig =
+        $"""<?xml version="1.0" encoding="utf-8"?>
+        <configuration>
+        <packageSources>
+        <clear />
+        <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" />
+        <add key="localBuild" value="{nugetPackageFolder}" />
+        </packageSources>
+        </configuration>
+        """
+
+    System.IO.File.WriteAllText(nugetConfigFilePath, nugetConfig)
+
 let runTemplate rootDir kind dependencies dsl =
     Directory.ensure rootDir
 
     try
+        writeTestNuGetConfig rootDir
+
         let result =
             DotNet.exec
                 (dotnetWorkingDir rootDir >> redirect ())