[main] Bump Microsoft.Identity.Web (#6927)

Bumps the identity-dependencies group in /eng/dependabot/independent with 1 update: [Microsoft.Identity.Web](https://github.com/AzureAD/microsoft-identity-web).


Updates `Microsoft.Identity.Web` from 2.19.1 to 2.20.0
- [Release notes](https://github.com/AzureAD/microsoft-identity-web/releases)
- [Changelog](https://github.com/AzureAD/microsoft-identity-web/blob/2.20.0/changelog.md)
- [Commits](https://github.com/AzureAD/microsoft-identity-web/commits/2.20.0)

---
updated-dependencies:
- dependency-name: Microsoft.Identity.Web
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: identity-dependencies
...

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

eng/dependabot/independent/Versions.props

@@ -5,7 +5,7 @@
     <AzureIdentityVersion>1.12.0</AzureIdentityVersion>
     <AzureStorageBlobsVersion>12.20.0</AzureStorageBlobsVersion>
     <AzureStorageQueuesVersion>12.18.0</AzureStorageQueuesVersion>
-    <MicrosoftIdentityWebVersion>2.19.1</MicrosoftIdentityWebVersion>
+    <MicrosoftIdentityWebVersion>2.20.0</MicrosoftIdentityWebVersion>
     <MicrosoftOpenApiReadersVersion>1.6.15</MicrosoftOpenApiReadersVersion>
     <SystemPrivateUriVersion>4.3.2</SystemPrivateUriVersion>
     <SystemSecurityPrincipalWindowsVersion>5.0.0</SystemSecurityPrincipalWindowsVersion>