Update pyo3 requirement from 0.7.0-alpha.1 to 0.8.0 (#324)

* Update pyo3 requirement from 0.7.0-alpha.1 to 0.8.0

Updates the requirements on [pyo3](https://github.com/pyo3/pyo3) to permit the latest version.
- [Release notes](https://github.com/pyo3/pyo3/releases)
- [Changelog](https://github.com/PyO3/pyo3/blob/master/CHANGELOG.md)
- [Commits](https://github.com/pyo3/pyo3/compare/v0.7.0-alpha.1...v0.8.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

* Change into_object() -> into_py()

misc/wasmtime-py/src/import.rs

@@ -62,7 +62,7 @@ unsafe extern "C" fn stub_fn(vmctx: *mut VMContext, call_id: u32, values_vec: *m
     let result = obj.call(py, PyTuple::new(py, args), None).expect("result");
     for i in 0..signature.returns.len() {
         let val = if result.is_none() {
-            0.into_object(py) // FIXME default ???
+            0.into_py(py) // FIXME default ???
         } else {
             if i > 0 {
                 panic!("multiple returns unsupported");
@@ -282,7 +282,7 @@ pub fn into_instance_from_obj(
 
             bound_functions.push(BoundPyFunction {
                 name: name.to_string(),
-                obj: item.into_object(py),
+                obj: item.into_py(py),
             });
         } else if item.get_type().is_subclass::<Memory>()? {
             let wasm_mem = item.cast_as::<Memory>()?;