Update Rx PackageReferences to 6.1.0 in integration tests (#2218)

Author: idg10

Rx.NET/Integration/LinuxTests/LinuxTests.csproj

@@ -28,8 +28,8 @@
     <PackageReference Include="MSTest.TestAdapter" Version="3.0.2" />
     <PackageReference Include="MSTest.TestFramework" Version="3.0.2" />
     <PackageReference Include="xunit.assert" Version="2.4.2" />
-    <PackageReference Include="System.Reactive" Version="6.0.2-preview*" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.2-preview*" />
-    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.0.2-preview*" />
+    <PackageReference Include="System.Reactive" Version="6.1.0-preview*" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.1.0-preview*" />
+    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.1.0-preview*" />
   </ItemGroup>
 </Project>

Rx.NET/Integration/WindowsDesktopTests/WindowsDesktopTests.csproj

@@ -27,8 +27,8 @@
     <PackageReference Include="MSTest.TestAdapter" Version="3.0.2" />
     <PackageReference Include="MSTest.TestFramework" Version="3.0.2" />
     <PackageReference Include="xunit.assert" Version="2.4.2" />
-    <PackageReference Include="System.Reactive" Version="6.0.2-preview*" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.0.2-preview*" />
-    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.0.2-preview*" />
+    <PackageReference Include="System.Reactive" Version="6.1.0-preview*" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="6.1.0-preview*" />
+    <PackageReference Include="System.Reactive.Observable.Aliases" Version="6.1.0-preview*" />
   </ItemGroup>
 </Project>