Update rack requirement from < 3 to < 4

[dependabot]

Updates the requirements on rack to permit the latest version.

Changelog

Sourced from rack's changelog.

[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.

[3.2.2] - 2025-10-07

Security

• CVE-2025-61772 Multipart parser buffers unbounded per-part headers, enabling DoS (memory exhaustion)
• CVE-2025-61771 Multipart parser buffers large non‑file fields entirely in memory, enabling DoS (memory exhaustion)
• CVE-2025-61770 Unbounded multipart preamble buffering enables DoS (memory exhaustion)

[3.2.1] -- 2025-09-02

Added

• Add support for streaming bodies when using Rack::Events. (#2375, @​unflxw)

Fixed

• Fix an issue where a NoMethodError would be raised when using Rack::Events with streaming bodies. (#2375, @​unflxw)

[3.2.0] - 2025-07-31

This release continues Rack's evolution toward a cleaner, more efficient foundation while maintaining backward compatibility for most applications. The breaking changes primarily affect deprecated functionality, so most users should experience a smooth upgrade with improved performance and standards compliance.

SPEC Changes

• Request environment keys must now be strings. (#2310, [@​jeremyevans])
• Add nil as a valid return from a Response body.to_path (#2318, [@​MSP-Greg])
• Rack::Lint#check_header_value is relaxed, only disallowing CR/LF/NUL characters. (#2354, [@​ioquatix])

Added

• Introduce Rack::VERSION constant. (#2199, [@​ioquatix])
• ISO-2022-JP encoded parts within MIME Multipart sections of an HTTP request body will now be converted to UTF-8. (#2245, @​nappa)
• Add Rack::Request#query_parser= to allow setting the query parser to use. (#2349, [@​jeremyevans])
• Add Rack::Request#form_pairs to access form data as raw key-value pairs, preserving duplicate keys. (#2351, [@​matthewd])

Changed

... (truncated)

Commits

• 4c24539 Bump patch version.
• 3ba5e4f Allow Multipart head to span read boundary. (#2392)
• 32bf888 Bump patch version.
• e179614 Unbounded read in Rack::Request form parsing can lead to memory exhaustion.
• 57277b7 Improper handling of proxy headers in Rack::Sendfile may allow proxy bypass.
• 403b74b Normalize adivsories links.
• fb395bb Fix handling of Errno::EPIPE in multipart tests.
• bce149b Bump patch version.
• 3beacfc Limit amount of retained data when parsing multipart requests
• 589127f Fix denial of service vulnerbilties in multipart parsing
• Additional commits viewable in compare view

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