Update dependency PuppeteerSharp to v21

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
PuppeteerSharp	20.2.6 → 21.0.1

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Release Notes

hardkoded/puppeteer-sharp (PuppeteerSharp)

v21.0.1

What's Changed

• Use stable WebDriverBiDi-Relaxed 0.0.41 by @​kblok in #​3125

Full Changelog: hardkoded/puppeteer-sharp@v21.0.0...v21.0.1

v21.0.0

New Features

• WebDriver BiDi protocol support for Firefox!!!!! PuppeteerSharp now supports the WebDriver BiDi protocol, enabling Firefox automation alongside existing Chrome/Chromium CDP support. Select the protocol via
  LaunchOptions.Protocol.
• New ProtocolType enum: ProtocolType.Cdp (default) and ProtocolType.WebdriverBiDi.

Breaking Changes

• AcceptInsecureCerts removed from IBrowser: This property was removed from the public interface. Insecure certs are now handled internally via the Security.setIgnoreCertificateErrors CDP command during browser creation.
• Non-generic EvaluateExpressionAsync() and EvaluateFunctionAsync() return type changed: Changed from Task<JsonElement?> to Task (void). If you need a return value, use the generic overloads EvaluateExpressionAsync() /
  EvaluateFunctionAsync().
• IBrowserContext now extends IDisposable and IAsyncDisposable: Browser contexts should now be properly disposed.
• Several protected methods on Page changed to internal: OnFrameAttached, OnFrameDetached, OnFrameNavigated, OnRequestFailed, OnRequestFinished, OnRequestServedFromCache, OnResponse, OnDOMContentLoaded, OnLoad. These were
  internal event-raising methods that should never have been protected.
• CDPSession.Close() signature changed: From internal abstract void Close() to public abstract void Close(string closeReason).

Minor Changes

• Dependency updates: System.Text.Json upgraded to 10.0.0, Microsoft.Bcl.AsyncInterfaces upgraded to 10.0.0.
• New dependency: WebDriverBiDi-Relaxed 0.0.40-beta.1 added for BiDi protocol support.
• Custom query handlers are now global: CustomQuerySelectorRegistry changed from connection-scoped to a global singleton.
• Frame.AddScriptTagAsync() is now a concrete implementation on the base Frame class instead of abstract.
• Package now includes README.md in the NuGet package.
• Fix flaky ShouldReportScriptsAcrossNavigationsWhenDisabled test: Added WaitForNetworkIdleAsync() between navigations to prevent coverage data loss.

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