[RELEASE] Released version 2.4.21

Released version 2.4.21 with the following main changes :
    - BUG/MINOR: http-htx: Don't consider an URI as normalized after a set-uri action
    - BUG/MEDIIM: stconn: Flush output data before forwarding close to write side
    - CI: github: change "ubuntu-latest" to "ubuntu-20.04"
    - BUILD: peers: peers-t.h depends on stick-table-t.h
    - BUG/MINOR: resolvers: Don't wait periodic resolution on healthcheck failure
    - BUG/MEDIUM: ssl: Verify error codes can exceed 63
    - BUG/MINOR: ssl: Fix potential overflow
    - BUG/MEDIUM: mworker: fix segv in early failure of mworker mode with peers
    - BUG/MINOR: promex: create haproxy_backend_agg_server_status
    - MINOR: promex: introduce haproxy_backend_agg_check_status
    - DOC: promex: Add missing backend metrics
    - BUG/MAJOR: fcgi: Fix uninitialized reserved bytes
    - REGTESTS: fix the race conditions in iff.vtc
    - REGTESTS: startup: check maxconn computation
    - BUG/MEDIUM: resolvers: Use tick_first() to update the resolvers task timeout
    - LICENSE: wurfl: clarify the dummy library license.
    - BUG/MINOR: ssl: Fix memory leak of find_chain in ssl_sock_load_cert_chain
    - BUG/MEDIUM: mux-h2: Refuse interim responses with end-stream flag set
    - BUG/MINOR: pool/stats: Use ullong to report total pool usage in bytes in stats
    - BUILD: makefile: build the features list dynamically
    - BUILD: makefile: sort the features list
    - BUG/MINOR: http-fetch: Only fill txn status during prefetch if not already set
    - BUG/MAJOR: buf: Fix copy of wrapping output data when a buffer is realigned
    - REGTEST: fix the race conditions in json_query.vtc
    - REGTEST: fix the race conditions in digest.vtc
    - REGTEST: fix the race conditions in hmac.vtc
    - BUG/MINOR: http: Memory leak of http redirect rules' format string
    - CLEANUP: htx: fix a typo in an error message of http_str_to_htx
    - BUG/MINOR: h1-htx: Remove flags about protocol upgrade on non-101 responses
    - BUG/MINOR: resolvers: Wait the resolution execution for a do_resolv action
    - BUG/MINOR: promex: Don't forget to consume the request on error
    - BUG/MINOR: http-ana: Report SF_FINST_R flag on error waiting the request body
    - BUG/MINOR: http-fetch: Don't block HTTP sample fetch eval in HTTP_MSG_ERROR state
    - BUG/MINOR: http-ana: make set-status also update txn->status
    - BUG/MINOR: listeners: fix suspend/resume of inherited FDs
    - DOC: config: fix wrong section number for "protocol prefixes"
    - DOC: config: fix aliases for protocol prefixes "udp4@" and "udp6@"
    - BUG/MINOR: mux-fcgi: Correctly set pathinfo
    - DOC: config: fix "Address formats" chapter syntax
    - BUG/MINOR: listener: close tiny race between resume_listener() and stopping
    - BUG/MINOR: mux-h2: add missing traces on failed headers decoding
    - BUILD: hpack: include global.h for the trash that is needed in debug mode
    - BUG/MINOR: sink: free the forwarding task on exit
5 files changed