[mbed-tls] Mbed TLS 2.7 end of support

This is a notice that Mbed TLS 2.7 will no longer be supported or maintained after February 5th 2021. Mbed TLS 2.7.0 was released on February 5th 2018 with a three year support period.

The current version of Mbed TLS 2.7 is 2.7.18, which was released on December 11th 2020. There are no pending bug or security fixes, so unless new issues arise during the next month, there will not be another release of 2.7. We do not plan to merge any non-critical backports to 2.7 in the next month.

We recommend that where practical, users upgrade to either 2.16, which will be supported until the end of 2021, or to the development branch, which will be released as an LTS in mid 2021, with an expected support period until mid 2024.

Dave Rodgman