Compilation error with pythonize 0.21 and pyo3 0.21.1

I've tried updating a private project to pyo3 0.21.1 and pythonize 0.21.0, but it fails to compile with the following issue: ``` error[E0599]: no method named `to_str` found for reference `&pyo3::Bound<'_, PyUnicode>` in the current scope --> /home/dobo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pythonize-0.21.0/src/de.rs:133:52 | 133 | let s = self.input.downcast::<PyString>()?.to_str()?; | ^^^^^^ help: there is a method with a similar name: `into_ptr` error[E0599]: no method named `to_str` found for reference `&pyo3::Bound<'_, PyUnicode>` in the current scope --> /home/dobo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pythonize-0.21.0/src/de.rs:156:29 | 156 | visitor.visit_str(s.to_str()?) | ^^^^^^ help: there is a method with a similar name: `into_ptr` error[E0599]: no method named `to_str` found for reference `&pyo3::Bound<'_, PyUnicode>` in the current scope --> /home/dobo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pythonize-0.21.0/src/de.rs:286:34 | 286 | visitor.visit_enum(s.to_str()?.into_deserializer()) | ^^^^^^ help: there is a method with a similar name: `into_ptr` error[E0599]: no method named `to_str` found for reference `&pyo3::Bound<'_, PyUnicode>` in the current scope --> /home/dobo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pythonize-0.21.0/src/de.rs:300:29 | 300 | visitor.visit_str(s.to_str()?) | ^^^^^^ help: there is a method with a similar name: `into_ptr` error[E0599]: no method named `to_str` found for struct `pyo3::Bound<'py, PyUnicode>` in the current scope --> /home/dobo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pythonize-0.21.0/src/de.rs:409:26 | 409 | self.variant.to_str()?.into_deserializer(); | ^^^^^^ help: there is a method with a similar name: `into_ptr` ``` Any idea what could be going wrong here?