Bump DT.Core to 3.9.0 (#1362)

Co-authored-by: Sophia Tevosyan <stevosyan@microsoft.com>

Author: sophiatev

src/DurableTask.Core/DurableTask.Core.csproj

@@ -16,7 +16,7 @@
   <!-- Version Info -->
   <PropertyGroup>
     <MajorVersion>3</MajorVersion>
-    <MinorVersion>8</MinorVersion>
+    <MinorVersion>9</MinorVersion>
     <PatchVersion>0</PatchVersion>
     <VersionPrefix>$(MajorVersion).$(MinorVersion).$(PatchVersion)</VersionPrefix>
     <FileVersion>$(VersionPrefix).0</FileVersion>