SSL: SSL_get_peer_certificate() is deprecated in OpenSSL 3.0.

Switch to SSL_get1_peer_certificate() when building with OpenSSL 3.0
and OPENSSL_NO_DEPRECATED defined.

src/event/ngx_event_openssl.h

diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h
index 7fb4c5f..a70b862 100644
--- a/src/event/ngx_event_openssl.h
+++ b/src/event/ngx_event_openssl.h
@@ -64,6 +64,11 @@
 #endif
 
 
+#if (OPENSSL_VERSION_NUMBER >= 0x30000000L && !defined SSL_get_peer_certificate)
+#define SSL_get_peer_certificate(s)  SSL_get1_peer_certificate(s)
+#endif
+
+
 typedef struct ngx_ssl_ocsp_s  ngx_ssl_ocsp_t;