Update NuGet packages

Update various NuGet packages to their latest versions.

Co-Authored-By: kinosang <[email protected]>

Author: martincostello

eng/Versions.props

@@ -10,12 +10,12 @@
   </PropertyGroup>
   <PropertyGroup>
     <AngleSharpVersion>0.9.9</AngleSharpVersion>
-    <AspNetCoreVersion>3.0.0</AspNetCoreVersion>
-    <IdentityModelCoreVersion>2.1.4</IdentityModelCoreVersion>
+    <AspNetCoreVersion>3.1.2</AspNetCoreVersion>
+    <IdentityModelCoreVersion>5.6.0</IdentityModelCoreVersion>
     <JetBrainsVersion>2019.1.3</JetBrainsVersion>
     <JustEatHttpClientInterceptionVersion>3.0.0</JustEatHttpClientInterceptionVersion>
     <MartinCostelloLoggingXUnitVersion>0.1.0</MartinCostelloLoggingXUnitVersion>
     <ShouldlyVersion>3.0.2</ShouldlyVersion>
-    <SystemTextJsonVersion>4.6.0</SystemTextJsonVersion>
+    <SystemTextJsonVersion>4.7.1</SystemTextJsonVersion>
   </PropertyGroup>
 </Project>