Vendor dependencies

Let's see how I like this workflow.

vendor/scratch/build.rs

@@ -0,0 +1,10 @@
+#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
+#![cfg_attr(feature = "cargo-clippy", allow(let_underscore_drop))]
+
+use std::{env, fs};
+
+fn main() {
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let _ = fs::remove_dir_all(&out_dir);
+    let _ = fs::create_dir(&out_dir);
+}