Update to Substrate v0.9.39

[mnaamani]

Mainnet was released using substrate from https://github.com/Joystream/substrate/tree/joystream-carthage commit Joystream/substrate@d29a53b
This was based off the substrate branch v0.9.24-1 with the patched vesting and staking pallet.

Since mainnet release many new versions of substrate have been released with many enhancements, bug fixes so we should update. At the time of writing we picked version used by polkadot v0.9.39 (for each polkadot release there is a new branch on the substrate repo matching the version) - we branched off and applied our staking pallet patch on top in https://github.com/Joystream/substrate/commits/joystream-polkadot-v0.9.39-update

Work on migrating to this new version is underway in branch https://github.com/Joystream/joystream/tree/update-to-polkadot-v0.9.39

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