feat(new parachain): show polkadot version

[CinematicCow]

This PR solves for #37. It fetches the latest tag from the repo that is cloned based on the template flag. The release tags are as follows:

Template	Tag
base	polkadot-v1.9.0
contract	v0.9.0
frontier	polkadot-v0.9.37

As each repo has it's own naming schema, how do we standardize the naming convention for the end user?

Also I saw there is already a function to get the release tag Github::get_latest_release using github's api, but that function was async and I am not familiar with async rust. Hope this PR helps :)

[Daanvdplas]

Hi @CinematicCow, amazing to see you again!

[weezy20]

Approach looks good.

1. Iterator should be in reverse order to search starting from latest release
2. fetch_tag and all consumers should return and expect an Option, in case the regex fails or template source doesn't use tags.