remove all references to Newtonsoft.Json

Author: jetersen

src/Directory.Build.props

@@ -21,7 +21,6 @@
         <PackageVersion_LibGit2Sharp_NativeBinaries>2.0.306</PackageVersion_LibGit2Sharp_NativeBinaries>
         <PackageVersion_JetBrainsAnnotations>2019.1.3</PackageVersion_JetBrainsAnnotations>
         <PackageVersion_YamlDotNet>8.0.0</PackageVersion_YamlDotNet>
-        <PackageVersion_NewtonsoftJson>12.0.3</PackageVersion_NewtonsoftJson>
 
         <PackageVersion_MicrosoftTestSdk>16.4.0</PackageVersion_MicrosoftTestSdk>
         <PackageVersion_NSubstitute>4.2.1</PackageVersion_NSubstitute>

src/GitVersionExe.Tests/ExecutionResults.cs

@@ -1,6 +1,6 @@
 using System.Collections.Generic;
-using Newtonsoft.Json;
 using GitVersion.OutputVariables;
+using System.Text.Json;
 
 namespace GitVersionExe.Tests
 {
@@ -21,7 +21,7 @@ public virtual VersionVariables OutputVariables
         {
             get
             {
-                var outputVariables = JsonConvert.DeserializeObject<Dictionary<string, string>>(Output);
+                var outputVariables = JsonSerializer.Deserialize<Dictionary<string, string>>(Output);
                 return VersionVariables.FromDictionary(outputVariables);
             }
         }

src/test.props

@@ -6,7 +6,6 @@
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="$(PackageVersion_MicrosoftTestSdk)" />
         <PackageReference Include="JetBrains.Annotations" Version="$(PackageVersion_JetBrainsAnnotations)"></PackageReference>
-        <PackageReference Include="Newtonsoft.Json" Version="$(PackageVersion_NewtonsoftJson)"></PackageReference>
         <PackageReference Include="NSubstitute" Version="$(PackageVersion_NSubstitute)"></PackageReference>
         <PackageReference Include="coverlet.msbuild" Version="$(PackageVersion_CoverletMsBuild)">
             <PrivateAssets>all</PrivateAssets>