Given code like the following
```
class Foo:
@process_cached
def bar(self):
pass
```
In Python 3.8 referencing `bar` would not call its `__get__` method.
```
x = Foo().bar
```
However in Python 3.11, making the same call would call the `__get__`
method, permanently replacing the underlying `process_cached` object
with the partial function that references it.
This meant that code to clear the cache would work in Python 3.8 but
would break in 3.11
```
Foo().bar.cache.clear() # Works in 3.8 but not in 3.11
```
In 3.11 this results in the following error:
```
E AttributeError: 'functools.partial' object has no attribute 'cache'
```
To make this compatible in both version, we just add the cache as an
accessible attribute on the partial we generate for our wrapped
function.
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