Bump bindgen to be able to handle CXCursor_LinkageSpec in LLVM18+ (#1243)

Current master branch gets stuck trying to compile `c2rust-ast-exporter`
in Archlinux.
The problem is that the bindgen version used by c2rust doesn't handle
the new Clang 18+'s `CXCursor_LinkageSpec` reported by
`clang::getCursorKindForDecl`.

rust-lang/rust-bindgen#2689 fixes the issue, so
I've bumped the bindgen version to the minimum that works.

Author: kkysen

Cargo.lock

@@ -18,7 +18,7 @@ serde_bytes = "0.11"
 serde_cbor = "0.11"
 
 [build-dependencies]
-bindgen = { version = "0.65", features = ["logging"] }
+bindgen = { version = "0.69.2", features = ["logging"] }
 clang-sys = "1.3"
 cmake = "0.1.49"
 env_logger = "0.10"