Update to pyo3 0.16 (#37)

Author: messense

Cargo.lock

@@ -7,7 +7,7 @@ edition = "2018"
 [dependencies]
 toml = {version = "0.5.8", features = ["preserve_order"]}
 serde = "1.0.126"
-pyo3 = {version = "0.14.1", features = ["extension-module"]}
+pyo3 = {version = "0.16.2", features = ["extension-module"]}
 
 [lib]
 name = "_rtoml"

Cargo.toml

@@ -77,7 +77,7 @@ impl<'p, 'a> Serialize for SerializePyObject<'p, 'a> {
 
         macro_rules! isa {
             ($v:ident, $t:ty) => {
-                $v.is_instance::<$t>().map_err(debug_py_err)?
+                $v.is_instance_of::<$t>().map_err(debug_py_err)?
             };
         }