Bump version to 3.1.8

Bump version to 3.1.8 for next release.

Author: martincostello

eng/Versions.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <MajorVersion>3</MajorVersion>
     <MinorVersion>1</MinorVersion>
-    <PatchVersion>7</PatchVersion>
+    <PatchVersion>8</PatchVersion>
     <VersionPrefix>$(MajorVersion).$(MinorVersion).$(PatchVersion)</VersionPrefix>
     <PreReleaseVersionLabel>preview</PreReleaseVersionLabel>
     <StabilizePackageVersion Condition="'$(StabilizePackageVersion)' == ''">true</StabilizePackageVersion>