Parse include!(<path/to/bracketed>)

For example:

    #[cxx::bridge]
    mod ffi {
        extern "C" {
            include!("path/to/quoted");
            include!(<path/to/bracketed>);

            ...
        }
    }

Emitted as:

    #include "path/to/quoted"
    #include <path/to/bracketed>
diff --git a/gen/src/write.rs b/gen/src/write.rs
index 0849d90..d5eae90 100644
--- a/gen/src/write.rs
+++ b/gen/src/write.rs
@@ -24,7 +24,7 @@
     out.include.extend(opt.include);
     for api in apis {
         if let Api::Include(include) = api {
-            out.include.insert(include.value());
+            out.include.insert(include);
         }
     }