Update 'main' branding to release/7.0-preview6 (#69813)

eng/Versions.props

@@ -8,7 +8,7 @@
     <PatchVersion>0</PatchVersion>
     <SdkBandVersion>7.0.100</SdkBandVersion>
     <PreReleaseVersionLabel>preview</PreReleaseVersionLabel>
-    <PreReleaseVersionIteration>5</PreReleaseVersionIteration>
+    <PreReleaseVersionIteration>6</PreReleaseVersionIteration>
     <!-- Set assembly version to align with major and minor version,
          as for the patches and revisions should be manually updated per assembly if it is serviced. -->
     <AssemblyVersion>$(MajorVersion).$(MinorVersion).0.0</AssemblyVersion>