This brings in a bugfix for analyzing variables inside relative traversal
expressions in HCL, and a cosmetic bugfix in cty for GoString of
cty.NullVal(cty.DynamicPseudoType).
This also updates some other packages, as a result of running "go get -u".
This includes a bugfix to the cty/msgpack package to ensure correct
decoding of unknown and null values.
This also includes updates to cty's dependencies.
John Houston