DataFrameSchema is not hashable

[sparkiegeek]

Describe the bug

DataFrameSchema is not hashable, and therefore cannot be used by e.g. functools.cache

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pandera.
• (optional) I have confirmed this bug exists on the main branch of pandera.

Code Sample, a copy-pastable example

import pandera as pa

schema = pa.DataFrameSchema({
    "column1": pa.Column(int)
})
hash(schema)

Expected behavior

Given that DataFrameSchema have good __str__ and __repr__s I'd have thought it would be straightforward to make them hashable, and therefore usable as dictionary keys and in turn cache'able.

As a local hack, I added the following monkey-patch

DataFrameSchema.__hash__ = lambda self: hash(repr(self))

which doesn't seem too terrible?

Desktop (please complete the following information):

• OS: WSL Ubuntu 24.04 LTS on Windows 11
• Browser: N/A
• Version: 0.22.1

Screenshots

N/A

Additional context

N/A