fix(github): use clang instead of gcc

[lklimek]

Issue being fixed or feature implemented

Build fails with:

error: failed to run custom build command for `bls-dash-sys v1.2.5 (https://github.com/dashpay/bls-signatures?branch=feat/threshold_bindings#198e246f)`

[...]

cc: error: unrecognized command-line option ‘-fembed-bitcode’

What was done?

Install and use clang

How Has This Been Tested?

GH actions

Breaking Changes

None

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone