Replaces uses of the github.com/mitchellh/mapstructure module, which
was deprecated by the owner and moved to new maintainership at
github.com/go-viper/mapstructure.
The old module is still referenced as indirect dependency (through
docker/cli and theupdateframework/notary), but not used in code, and
should eventually go away.
full diff: https://github.com/compose-spec/compose-go/compare/v2.1.1...v2.1.2
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
