openvpn: Update to version 2.7.3

openvpn: Update to version 2.7.3

- Update from version 2.7.1 to 2.7.3
- No change to rootfile
- 2 CVE fixes in 2.7.2. These have also been applied to 2.6.20 on the 2.6 branch
- Changelog
2.7.3
bugfixes
	in combination with --management-query-passwords, setups using --auth-user-pass
	 file or inline auth-user-pass would no longer use the configured passwords and
	 prompt on the management interface instead (OpenVPN GUI would then provide an
	 empty user/password prompt) (Github: OpenVPN/openpvn#1021).
2.7.2
Security fixes
    fix race condition in TLS handshake that could lead to leaking of packet data from
	a previous handshake under specific circumstances (CVE-2026-40215)
        (Bug found by XlabAI Team of Tencent Xuanwu Lab (xlabai@tencent.com))
    fix server ASSERT() on receiving a suitably malformed packet with a valid
	tls-crypt-v2 key (CVE-2026-35058)
        (Bug found by XlabAI Team of Tencent Xuanwu Lab (xlabai@tencent.com)
        and independently by Emma Reuter of Cisco ASIG (TALOS-2026-2381))
Bugfixes
    when using a config file with inlined username and no password, fix prompting for
	the password from management interface.
    Windows: fix DNSSEC flag handling - this got never applied due to a bad comparison
	being always false.
    Windows: fix deinstallation progress bar on adapter deletion.
New features
    management interface: permit input of very long passwords in base64-encoded
	multiline format. Signal support to management clients via
	"management version 6".
Documentation
    improve documentation and error messages related to old and new Linux DCO modules
    remove some references to pre-2.3 OpenVPN
    improve manpage for --learn-address config
User-visible Changes
    improve error messages on --verify-x509-name failures
    improve error logging when overlong username or passwords can not be written to TLS
	buffer
Long-term code maintenance
    fully support OpenSSL 4.0 now, without "deprecated API" warnings (multiple small
	changes to adapt to 3.5 -> 4.0 API changes)
    add unit tests for certificate detail printing
    add unit tests for "empty password on inline credentials" handling

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>