cleanup: remove unused dependencies

```console
warning: unused dependency `libc`
  --> ctest-test/Cargo.toml:16:1
   |
16 | libc = { path = ".." }
   | ^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `cargo::unused_dependencies` is set to `warn` by default
```

[ edited commit tag - Trevor ]

Author: xtqqczze

Cargo.lock

@@ -12,9 +12,6 @@ cc = "1.4.2"
 [dev-dependencies]
 ctest = { path = "../ctest" }
 
-[dependencies]
-libc = { path = ".." }
-
 [[bin]]
 name = "t1"
 test = false