This implies some notable changes that will have a visible impact to
end-users of official Terraform releases:

- Terraform is no longer compatible with MacOS 10.10 Yosemite, and
  requires at least 10.11 El Capitan. (Relatedly, Go 1.14 is planned to be
  the last release to support El Capitan, so while that remains supported
  for now, it's notable that Terraform 0.13 is likely to be the last major
  release of Terraform supporting it, with 0.14 likely to further require
  MacOS 10.12 Sierra.)

- Terraform is no longer compatible with FreeBSD 10.x, which has reached
  end-of-life. Terraform now requires FreeBSD 11.2 or later.

- Terraform now supports TLS 1.3 when it makes connections to remote
  services such as backends and module registries. Although TLS 1.3 is
  backward-compatible in principle, some legacy systems reportedly work
  incorrectly when attempting to negotiate it. (This change does not
  affect outgoing requests made by provider plugins, though they will see
  a similar change in behavior once built with Go 1.13 or later.)

- Ed25519 certificates are now supported for TLS 1.2 and 1.3 connections.

- On UNIX systems where "use-vc" is set in resolv.conf, TCP will now be
  used for DNS resolution. This is unlikely to cause issues in practice
  because a system set up in this way can presumably already reach its
  nameservers over TCP (or else other applications would misbehave), but
  could potentially lead to lookup failures in unusual situations where a
  system only runs Terraform, has historically had "use-vc" in its
  configuration, but yet is blocked from reaching its configured
  nameservers over TCP.

- Some parts of Terraform now support Unicode 12.0 when working with
  strings. However, notably the Terraform Language itself continues to
  use the text segmentation tables from Unicode 9.0, which means it lacks
  up-to-date support for recognizing modern emoji combining forms as
  single characters. (We may wish to upgrade the text segmentation tables
  to Unicode 12.0 tables in a later commit, to restore consistency.)

This also includes some changes to the contents of "vendor", and
particularly to the format of vendor/modules.txt, per the changes to
vendoring in the Go 1.14 toolchain. This new syntax is activated by the
specification of "go 1.14" in the go.mod file.

Finally, the exact format of error messages from the net/http library has
changed since Go 1.12, and so a couple of our tests needed updates to
their expected error messages to match that.