Secure the update chainspec process

[wirednkod]

So far the update-chainspec-process runs every day for keeping the specs up to date with the latest state of each chain provided.

We need to make this process more secure (and if possible even more automated), with verified commits or with an automated Parity bot instead of a random account.

[wirednkod]

Adding the respective IT issue here: https://github.com/paritytech/internal_it/issues/229 for tracking purposes