Improve coverage of `_collections_abc._CallableGenericAlias`

[sobolevn]

Right now several important implementation details of this type is not covered:

1. Pickle with ParamSpec

2. Invalid type argument

Related to #102615 where this was originally discovered.
I will send a PR shortly.

Linked PRs

• gh-102721: Improve coverage of _collections_abc._CallableGenericAlias #102722
• [3.11] gh-102721: Improve coverage of _collections_abc._CallableGenericAlias #102788
• [3.10] gh-102721: Improve coverage of _collections_abc._CallableGenericAlias #102790