[release/8.x] Bump the runtime-dependencies group with 1 update

Bumps Microsoft.NETCore.DotNetHost from 8.0.20 to 8.0.21

---
updated-dependencies:
- dependency-name: Microsoft.NETCore.DotNetHost
  dependency-version: 8.0.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: runtime-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

eng/dependabot/net8.0/Versions.props

@@ -10,7 +10,7 @@
     <!-- Microsoft.Extensions.Logging.Console -->
     <MicrosoftExtensionsLoggingConsole80Version>8.0.1</MicrosoftExtensionsLoggingConsole80Version>
     <!-- Microsoft.NETCore.App -->
-    <MicrosoftNETCoreApp80Version>8.0.20</MicrosoftNETCoreApp80Version>
+    <MicrosoftNETCoreApp80Version>8.0.21</MicrosoftNETCoreApp80Version>
     <!-- System.Text.Json -->
     <SystemTextJson80Version>8.0.6</SystemTextJson80Version>
   </PropertyGroup>