Check for TLS 1.3

[ChargingBulle]

TLS 1.3 is the new encryption standard which many browsers and many webservers already support.
It was released in August 2018 and I propose to add this as an "just for information"-Field on PrivacyScore.

_{Some more infos for those who are interested:}

• IETF on TLS 1.3
• CCC Talk "The Rocky Road to TLS 1.3 and better Internet Encryption" (60 min)
• Some blog which compares V1.2 and V1.3

[hprid]

We rely on testssl.sh for our TLS checks. Unfortunately, we are stuck at an older testssl.sh version which does not support TLS 1.3 yet. Updating testssl.sh to a new version is not quite easy, since the JSON format, which we use to read the data from testssl.sh, has been changed. We have a new scanning engine in development which uses the most current testssl.sh (v3.0 alpha). Once that is ready, we show information about TLS 1.3 and more (e.g. OCSP stapling)