write CI which installs and executes a local electrum server on regtest

[gorazdko]

Abstract

Currently we can execute tests locally with

cargo test

In addition, we can test with:

cargo test --features nigiri

which requires a local electrum server on regtest, called nigiri: https://github.com/vulpemventures/nigiri

The CI to use should be Github Actions, see an example here: https://github.com/BlockchainCommons/musign-cli/blob/master/.github/workflows/Build.yml

Both commands (cargo test and cargo test --features nigiri) should run successfully in CI

[HarshCasper]

Can I please take it up? I will be working as a Software Developer Intern with Blockchain Commons.