Enable deterministic settings

Ix.NET/Source/Directory.build.props

@@ -21,12 +21,16 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(TF_BUILD)' == 'true'">
+    <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>
+    <Deterministic>true</Deterministic>
+  </PropertyGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
     <PackageReference Include="Nerdbank.GitVersioning" Version="3.1.71" PrivateAssets="all" />
   </ItemGroup>
 
-
   <ItemGroup Condition="'$(IsTestProject)' == 'true'">
     <PackageReference Include="coverlet.collector" Version="1.2.0" />
   </ItemGroup>

Rx.NET/Source/Directory.build.props

@@ -22,6 +22,10 @@
     <LangVersion>latest</LangVersion>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(TF_BUILD)' == 'true'">
+    <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>
+    <Deterministic>true</Deterministic>
+  </PropertyGroup>
 
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>