Bump OpenNext to 1.6.4

[conico974]

Update dependencies to use specific versions from OpenNext to include the fix for this error TypeError: This ReadableStream is currently locked to a reader.

[linear]

RND-7817 Fix `TypeError: This ReadableStream is currently locked to a reader.`in GBO 2c

[changeset-bot]

⚠️ No Changeset found

Latest commit: 2996c7a

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[github-actions]

Summary of the deployments:

Version	URL	Status
Vercel	https://gitbook-v2-7xfo9q9r9-gitbook.vercel.app	✅
Cloudflare	https://30b9985f-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	2v	2c
GitBook	https://gitbook-v2-7xfo9q9r9-gitbook.vercel.app/url/gitbook.com/docs	https://30b9985f-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.com/docs
E2E	https://gitbook-v2-7xfo9q9r9-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open	https://30b9985f-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.gitbook.io/test-gitbook-open

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Build	Status	Details	Updated (UTC)
customers-v2 (Inspect)	✅ No changes detected	-	Aug 4, 2025, 6:49 PM
v2-cloudflare (Inspect)	👍 Changes approved	2 changed	Aug 4, 2025, 6:56 PM
v2-vercel (Inspect)	👍 Changes approved	2 changed	Aug 4, 2025, 7:22 PM