Revert to use InspectCmd, bump substrate `6bef4f4` (#966)

* revert to use InspectCmd

* rust toolchain 1.52

* Bump `finality-grandpa` and `parity-scale-codec`

* bump to same version for substrate as polkadot v0.9.1

* bump to polkadot 0.9.2 deps for substrate `6bef4f4`

Co-authored-by: Hernando Castano <hernando@hcastano.com>