nghttp2 v1.55.0

What's Changed

• Fix build error without libev by @tatsuhiro-t in #1915
• Bump go to 1.20 by @tatsuhiro-t in #1916
• Bump go package dependencies by @tatsuhiro-t in #1917
• mruby: Support cross build for autotools by @tatsuhiro-t in #1918
• h2load, nghttpx: Add UDP_GRO support by @tatsuhiro-t in #1920
• Bump ngtcp2 by @tatsuhiro-t in #1923
• nghttpx: Randomize initial QUIC packet number by @tatsuhiro-t in #1925
• Bump llhttp to a0e744f850d8101a51284868ffdf745bcfe4fbcc by @tatsuhiro-t in #1926
• Bump macos to 12 by @tatsuhiro-t in #1927

Full Changelog: v1.54.0...v1.55.0