nghttp3 v1.18.0

What's Changed

• ksl: Align keys in 8 bytes boundary by @tatsuhiro-t in #534
• Update doc by @tatsuhiro-t in #536
• Add nghttp3_conn_close_stream2 and nghttp3_stream_close2 callback by @tatsuhiro-t in #537
• Update doc by @tatsuhiro-t in #538
• Validate header length against the estimated uncompressed length by @tatsuhiro-t in #539
• ksl: Port ngtcp2 changes by @tatsuhiro-t in #540
• Document C compilers by @tatsuhiro-t in #541
• Fix build error with gcc-16 by @tatsuhiro-t in #542

Full Changelog: v1.17.0...v1.18.0