[AI] Fix Typos

[KCarretto]

This PR fixes several typos found in the codebase and documentation to adhere to American English spelling conventions.

Modifications:

• docs/_config.yml: grey -> gray
• docs/_includes/scrolltop.html: grey -> gray
• tavern/config.go: behaviour -> behavior
• tavern/cli/auth/auth.go: authentication cancelled -> authentication canceled
• tavern/internal/redirectors/http1/grpc_stream_test.go: cancelled -> canceled
• tavern/internal/auth/oauth_test.go: behaviour -> behavior
• tavern/internal/portals/mux/benchmark_test.go: cancelled -> canceled
• tavern/internal/errors/http_test.go: behaviour -> behavior

Ran go fmt ./... and go test ./... in tavern.
Deleted temporary scripts scan_typos.py and scan_typos_v2.py.

---

PR created automatically by Jules for task 5398432195582195875 started by @KCarretto

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.

[github-actions]

Summary

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
2564    ±0	2564    ±0	0    ±0	0    ±0	0    ±0	0    ±0	1ms    ±0

Previous Results

Build 🏗️	Result 🧪	Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
#956	✅	2564	2564	0	0	0	0	19.1s

Insights

Average Tests per Run	Total Flaky Tests	Total Failed	Slowest Test (p95)
2564	0	0	5.2s

Slowest Tests

Test 📝	Results 📊	Duration (avg) ⏱️	Duration (p95) ⏱️
eldritch-libsys: std::dll_inject_impl::tests::test_dll_inject_simple	1	5.2s	5.2s
imix::bin/imix: install::tests::test_install_execution	3	1.2s	3.3s
imix::bin/imix: install::tests::test_install_execution	3	1.2s	3.3s
imix::bin/imix: install::tests::test_install_execution	3	1.2s	3.3s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_output	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_output	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_output	3	3.0s	3.0s

_{🎉 No failed tests in this run. | 🍂 No flaky tests in this run.}

Github Test Reporter by CTRF 💚