This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
This changes the approach used by the provider installer to remember
between runs which selections it has previously made, using the lock file
format implemented in internal/depsfile.
This means that version constraints in the configuration are considered
only for providers we've not seen before or when -upgrade mode is active.
Martin Atkins