vet workspace dependencies (#163)

- Update the used workspace dependencies.
- Remove the unused workspace dependencies.
- Add the machete CI workflow.

crates/llvm-builder/Cargo.toml

@@ -30,10 +30,8 @@ regex = { workspace = true }
 downloader = { workspace = true }
 tar = { workspace = true }
 flate2 = { workspace = true }
-http = { workspace = true }
 env_logger = { workspace = true }
 log = { workspace = true }
-once_cell = { workspace = true }
 
 [dev-dependencies]
 assert_cmd = { workspace = true }