Update package:web_benchmarks dep.

[ditman]

This change is in preparation of the removal of --web-renderer=html.

• Related: [web_benchmarks] Remove WebRenderer enum. packages#8103 (tooling change to remove the parameter from the benchmark runner)
• Related: ☂️ Intent to deprecate and remove the HTML renderer in Flutter Web flutter#145954 (general thread)

Tests

In this case, CI should continue normally. The change is just adopting a new major version of package:web_benchmarks that removed some public API (that wasn't used in devtools).

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read the Flutter Style Guide recently, and have followed its advice.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or there is a reason for not adding tests.

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