Update dependencies from https://github.com/dotnet/iot build 20190701.6

- Iot.Device.Bindings - 0.1.0-prerelease.19351.6
- System.Device.Gpio - 0.1.0-prerelease.19351.6

eng/Version.Details.xml

 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
   <ProductDependencies>
-    <Dependency Name="System.Device.Gpio" Version="0.1.0-prerelease.19351.1">
+    <Dependency Name="System.Device.Gpio" Version="0.1.0-prerelease.19351.6">
       <Uri>https://github.com/dotnet/iot</Uri>
-      <Sha>ce75ecb21964bd6ddf3e168033fc4ac4a18a65d2</Sha>
+      <Sha>3626cc63ce192388b87c509d9d64ea9baa930f7c</Sha>
     </Dependency>
-    <Dependency Name="Iot.Device.Bindings" Version="0.1.0-prerelease.19351.1">
+    <Dependency Name="Iot.Device.Bindings" Version="0.1.0-prerelease.19351.6">
       <Uri>https://github.com/dotnet/iot</Uri>
-      <Sha>ce75ecb21964bd6ddf3e168033fc4ac4a18a65d2</Sha>
+      <Sha>3626cc63ce192388b87c509d9d64ea9baa930f7c</Sha>
     </Dependency>
   </ProductDependencies>
   <ToolsetDependencies>

eng/Versions.props

@@ -3,8 +3,8 @@
   <PropertyGroup>
     <PreReleaseVersionLabel>prerelease</PreReleaseVersionLabel>
     <!-- dotnet/iot dependencies -->
-    <SystemDeviceGpioPackageVersion>0.1.0-prerelease.19351.1</SystemDeviceGpioPackageVersion>
-    <IotDeviceBindingsPackageVersion>0.1.0-prerelease.19351.1</IotDeviceBindingsPackageVersion>
+    <SystemDeviceGpioPackageVersion>0.1.0-prerelease.19351.6</SystemDeviceGpioPackageVersion>
+    <IotDeviceBindingsPackageVersion>0.1.0-prerelease.19351.6</IotDeviceBindingsPackageVersion>
     <!-- dotnet/arcade dependencies -->
     <MicrosoftDotNetGenAPIPackageVersion>1.0.0-beta.19330.1</MicrosoftDotNetGenAPIPackageVersion>
   </PropertyGroup>