Use DBPath in PinnableSlice test

tests/test_pinnable_slice.rs

@@ -1,14 +1,16 @@
 extern crate rocksdb;
+mod util;
 
 use rocksdb::{Options, DB};
+use util::DBPath;
 
 #[test]
 fn test_pinnable_slice() {
-    let path = "_rust_rocksdb_pinnable_slice_test";
+    let path = DBPath::new("_rust_rocksdb_pinnable_slice_test");
 
     let mut opts = Options::default();
     opts.create_if_missing(true);
-    let db = DB::open(&opts, path).unwrap();
+    let db = DB::open(&opts, &path).unwrap();
 
     db.put(b"k1", b"value12345").unwrap();