fix: reduce logging

If we can't debug_log because we couldn't obtain some data, but otherwise the app is working, "warning" level is clearly excessive.

src/pgp/gpg.c

@@ -664,7 +664,8 @@ p_gpg_decrypt(const char* const cipher)
                 }
                 gpgme_key_unref(key);
             } else if (error) {
-                log_warning("GPGME error: %s", gpgme_strerror(error));
+                // Emails are used only to fetch PGP recipients for debug logging. If something went wrong here, it's not worthy of warning.
+                log_debug("GPGME error on gpgme_get_key(): %s", gpgme_strerror(error));
             }
 
             if (recipient->next) {