[main] Update to the final net7 release (dotnet#42471)

Author: marcpopMSFT

eng/Versions.props

@@ -33,7 +33,7 @@
     <VersionFeature31>32</VersionFeature31>
     <VersionFeature50>17</VersionFeature50>
     <VersionFeature60>32</VersionFeature60>
-    <VersionFeature70>19</VersionFeature70>
+    <VersionFeature70>20</VersionFeature70>
     <VersionFeature80>7</VersionFeature80>
     <!-- Should be kept in sync with VersionFeature70. It should match the version of Microsoft.NET.ILLink.Tasks
          referenced by the same 7.0 SDK that references the 7.0.VersionFeature70 runtime pack. -->