0.21.0-rc.0 / 2022-05-10

This Prometheus release is built with go1.18, which contains two noticeable
changes related to TLS and HTTP:

1. TLS 1.0 and 1.1 disabled by default client-side.
   Blackbox Exporter users can override this with the min_version parameter of
   tls_config.
2. Certificates signed with the SHA-1 hash function are rejected.
   This doesn't apply to self-signed root certificates.

• [BUGFIX] Prevent setting negative timeouts when using a small scrape interval. #869