Remove dependency on specific version of capstone

Currently the callgraph library has a very specific dependency on the capstone library:

```
capstone = { git = "https://github.com/capstone-rust/capstone-rs.git", rev = "dc10578aa27414afc93f0a87959b2f0c22dc66c3" }
```

Newer version of this library changed their API to include lifetimes.

The code in the callgraph library needs refactoring to accept a newer capstone version. 