stunnel: update version to 5.75

stunnel: update version to 5.75

Bugfixes:
* Fixed infinite loop triggered by OCSP URL parsing errors (thx to Richard Könning for reporting).
* Fixed OPENSSL_NO_OCSP build issues (thx to Dmitry Mostovoy for reporting).
* Fixed default curve selection in FIPS mode with OpenSSL 3.4+.
* Fixed tests with modern Python versions.
* Fixed tests with multiple OpenSSL versions installed.

Features:
* Added provider URI support for "cert" and "key" options.
* Added new "CAstore" service-level option (OpenSSL 3.0+).
* Added "provider" (OpenSSL 3.0+), "providerParameter" (OpenSSL 3.5+), and "setEnv" global options.
* Key file/URI path added to passphrase prompt on Unix.
* PKCS#11 provider installed on Windows.

Signed-off-by: Florian Eckert <[email protected]>