[main] Bump Microsoft.OpenApi.Readers in /eng/dependabot/independent (#7234)

Bumps [Microsoft.OpenApi.Readers](https://github.com/Microsoft/OpenAPI.NET) from 1.6.18 to 1.6.19.
- [Release notes](https://github.com/Microsoft/OpenAPI.NET/releases)
- [Commits](https://github.com/Microsoft/OpenAPI.NET/compare/1.6.18...1.6.19)

---
updated-dependencies:
- dependency-name: Microsoft.OpenApi.Readers
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

eng/dependabot/independent/Versions.props

@@ -7,7 +7,7 @@
     <AzureStorageBlobsVersion>12.21.2</AzureStorageBlobsVersion>
     <AzureStorageQueuesVersion>12.19.1</AzureStorageQueuesVersion>
     <MicrosoftIdentityWebVersion>3.1.0</MicrosoftIdentityWebVersion>
-    <MicrosoftOpenApiReadersVersion>1.6.18</MicrosoftOpenApiReadersVersion>
+    <MicrosoftOpenApiReadersVersion>1.6.19</MicrosoftOpenApiReadersVersion>
     <SystemPrivateUriVersion>4.3.2</SystemPrivateUriVersion>
     <SystemSecurityPrincipalWindowsVersion>5.0.0</SystemSecurityPrincipalWindowsVersion>