Update github.com/imdario/mergo version

Gopkg.lock

Gopkg.toml

vendor/github.com/imdario/mergo/issue17_test.go

vendor/github.com/imdario/mergo/issue23_test.go

vendor/github.com/imdario/mergo/issue33_test.go

vendor/github.com/imdario/mergo/issue38_test.go

vendor/github.com/imdario/mergo/issue50_test.go

vendor/github.com/imdario/mergo/issue52_test.go

vendor/github.com/imdario/mergo/issue61_test.go

vendor/github.com/imdario/mergo/issue64_test.go

vendor/github.com/imdario/mergo/issue66_test.go

vendor/github.com/imdario/mergo/issue84_test.go

vendor/github.com/imdario/mergo/map.go

vendor/github.com/imdario/mergo/merge.go

vendor/github.com/imdario/mergo/merge_appendslice_test.go

vendor/github.com/imdario/mergo/merge_test.go

vendor/github.com/imdario/mergo/mergo.go

vendor/github.com/imdario/mergo/mergo_test.go

vendor/github.com/imdario/mergo/pr80_test.go

vendor/github.com/imdario/mergo/pr81_test.go