chore: bump rack from 2.2.20 to 2.2.22 in /examples/ruby/backend

[dependabot]

Bumps rack from 2.2.20 to 2.2.22.

Changelog

Sourced from rack's changelog.

Changelog

All notable changes to this project will be documented in this file. For info on how to format all future additions to this file please reference Keep A Changelog.

Unreleased

Security

• CVE-2025-61780 Improper handling of headers in Rack::Sendfile may allow proxy bypass.
• CVE-2025-61919 Unbounded read in Rack::Request form parsing can lead to memory exhaustion.
• CVE-2026-25500 XSS injection via malicious filename in Rack::Directory.
• CVE-2026-22860 Directory traversal via root prefix bypass in Rack::Directory.

SPEC Changes

• Define rack.response_finished callback arguments more strictly. (#2365, @​skipkayhil)

Added

• Add Rack::Files#assign_headers to allow overriding how the configured file headers are set. (#2377, @​codergeek121)
• Add support for rack.response_finished to Rack::TempfileReaper. (#2363, @​skipkayhil)
• Add support for streaming bodies when using Rack::Events. (#2375, @​unflxw)
• Add deflaters option to Rack::Deflater to enable custom compression algorithms like zstd. (#2168, @​alexanderadam)
• Add Rack::Request#prefetch? for identifying requests with Sec-Purpose: prefetch header set. (#2405, @​glaszig)
• Add rack.request.trusted_proxy environment key to indicate whether the request is coming from a trusted proxy.

Changed

• Raise before exceeding a part limit, not after. (#2362, @​matthew-puku)
• Rack::Deflater now uses a fixed GZip mtime value. (#2372, @​bensheldon)
• Multipart parser drops support for RFC 2231 filename* parameter (prohibited by RFC 7578) and now properly handles UTF-8 encoded filenames via percent-encoding and direct UTF-8 bytes. (#2398, @​wtn)
• The query parser now raises Rack::QueryParser::IncompatibleEncodingError if we try to parse params that are not ASCII compatible. (#2416, @​bquorning)

Fixed

• Multipart parser: limit MIME header size check to the unread buffer region to avoid false multipart mime part header too large errors when previously read data accumulates in the scan buffer. (#2392, @​alpaca-tc, @​willnet, @​krororo)
• Fix Rack::MockResponse#body when the body is a Proc. (#2420, #2423, @​tavianator, [@​ioquatix])

[3.2.4] - 2025-11-03

Fixed

• Multipart parser: limit MIME header size check to the unread buffer region to avoid false multipart mime part header too large errors when previously read data accumulates in the scan buffer. (#2392, @​alpaca-tc, @​willnet, @​krororo)

[3.2.3] - 2025-10-10

Security

• CVE-2025-61780 Improper handling of headers in Rack::Sendfile may allow proxy bypass.
• CVE-2025-61919 Unbounded read in Rack::Request form parsing can lead to memory exhaustion.

... (truncated)

Commits

• 0cc2e00 Bump patch version.
• a5725c0 Prevent directory traversal via root prefix bypass.
• 175e7d2 XSS injection via malicious filename in Rack::Directory.
• 3472037 Fix changelog.
• 851dc02 Bump patch version.
• 1e6aeda Allow Multipart head to span read boundary. (#2392)
• See full diff in compare view

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