Release 2026.8.0-rc4

See https://next.goauthentik.io/docs/releases/2026.8

What's Changed

• website/docs: fix sidebar titles and ordering (cherry-pick #24051 to version-2026.8) by @authentik-cherry-pick[bot] in #24700
• ci: release publish: fix metadata parsing by @rissson in #24703

Full Changelog: version/2026.8.0-rc3...version/2026.8.0-rc4