Use the stronger certificate fingerprint.

If a cert has a SHA256 use that one and only use SHA1 as fallback.

Closes: https://github.com/profanity-im/profanity/issues/2068
Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

src/config/tlscerts.h

@@ -41,6 +41,7 @@
 typedef struct tls_cert_t
 {
     int version;
+    const char* fingerprint;
     char* serialnumber;
     char* subjectname;
     char* subject_country;