Remove specialization from IntoPy implementation

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 
 * The blanket implementations for `FromPyObject` for `&T` and `&mut T` are no longer specializable. Implement `PyTryFrom` for your type to control the behavior of `FromPyObject::extract()` for your types.
+* The implementation for `IntoPy<U> for T` where `U: FromPy<T>` is no longer specializable. Control the behavior of this via the implementation of `FromPy`.
 
 ## [0.8.5]
 

src/conversion.rs

@@ -146,7 +146,7 @@ impl<T, U> IntoPy<U> for T
 where
     U: FromPy<T>,
 {
-    default fn into_py(self, py: Python) -> U {
+    fn into_py(self, py: Python) -> U {
         U::from_py(self, py)
     }
 }