Update v8 used during fuzzing (#3493)

This commit updates the crate name from `rusty_v8` to `v8` as well since
the upstream bindings have sinced moved. I originally wanted to do this
to see if a fix for one of our fuzz bugs was pulled in but I don't think
the fix has been pulled in yet. Despite that it seems reasonable to go
ahead and update.

crates/fuzzing/src/oracles/v8.rs

@@ -1,5 +1,4 @@
 use super::{first_exported_function, first_exported_memory, log_wasm};
-use rusty_v8 as v8;
 use std::convert::TryFrom;
 use std::sync::Once;
 use wasmtime::*;