Removes --insecure curl option

`curl` calls were using the `--insecure` option that makes `curl` ignore any certificate issues.
When first releasing this script, the *smsapi.free-mobile.fr* was not serving a valid/trusted SSL/TLS certificate, so `--insecure` was used to avoid getting normal but noisy errors.
Today, it seems *smsapi.free-mobile.fr*'s SSL/TLS issues are solved, so `--insecure` is not relevant anymore.

This commit removes the insecure `--insecure` option.

Closes: #2

send-notification.sh

@@ -148,15 +148,11 @@ FINAL_MESSAGE_TO_SEND=$(\
 # echo "${FINAL_MESSAGE_TO_SEND}" #DEBUG
 
 # Particularités de l'appel de curl et la/les options associées :
-# * Le certificat de $SMSAPI_BASEURL ne fourni pas d'informations sur son
-#   propriétaire :
-#       --insecure
 # * Renvoi le code réponse HTTP uniquement :
 #       --write-out "%{http_code}" --silent --output /dev/null
 #
 HTTP_STATUS_CODE=$(\
     curl \
-        --insecure \
         --write-out "%{http_code}" \
         --silent \
         --output /dev/null \