Make jsonify tolerant of differing-but-valid PyPhi versions

[rogerSuperBuilderAlpha]

Problem

jsonify._check_version requires the version string embedded in serialized JSON to exactly equal the running PyPhi version:

if version != PYPHI_VERSION:
    raise pyphi.exceptions.JSONVersionError(...)

The package version is derived from the latest git tag via hatch-vcs. On a fresh clone of feature/iit-4.0 (which has no 2.0.0a1 tag — the latest semver tag is 1.2.1), the reported version is something like 1.2.1.dev1470+gb78d0e34. The committed JSON test fixtures, however, are stamped "__version__": "2.0.0a1". The exact-string comparison therefore rejects them, and 22 tests fail on a clean checkout for any contributor:

pyphi.exceptions.JSONVersionError: Cannot load JSON from a different version of PyPhi.
JSON version = 2.0.0a1, current version = 1.2.1.dev1470+gb78d0e34.

Change

This loosens the check, in the spirit of the existing # TODO: somehow check schema instead of version? in jsonify.py:

• A version that parses as a valid PEP 440 version but differs from the current one now emits a warnings.warn(...) and loads on a best-effort basis, since the on-disk schema is stable across releases.
• A version string that cannot be parsed at all (e.g. "0.1.bogus") still raises JSONVersionError, so the existing guard — and test_version_check_during_deserialization — is preserved.

Notes

• Adds packaging to runtime dependencies (now imported by jsonify for version parsing; it is already universally present transitively).
• Adds a regression test for the warn-and-load path.
• Adds a changelog entry.

Verification

On Python 3.12 / feature/iit-4.0, the core suite (pytest test pyphi, excluding the optional ray/redis test modules) goes from 22 failures/errors → 0 attributable to this issue, with no regressions. (One unrelated pre-existing failure, test_distribution.py::test_unflatten, remains and is out of scope here.)