Upgrade autocxx-bindgen.
This brings in a version which adds extra annotations for references
vs pointers which we will use in a subsequent PR.
@@ -32,7 +32,7 @@ proc-macro2 = "1.0"
quote = "1.0"
lazy_static = "1.4"
indoc = "1.0"
-autocxx-bindgen = "0.56.1"
+autocxx-bindgen = "0.57.0"
itertools = "0.9"
dunce = "1.0.1"
cc = { version = "1.0", optional = true }
