fix: cap exca to restore a working clean install

[adi-suresh01]

Summary

A clean install of tribev2 currently fails at import time because of an exca API change. This caps exca to a compatible range so a fresh install works again, and declares exca as an explicit dependency since the package imports it directly.

Closes #65 (also addresses the install failures reported in #2 and #27's environment).

Root cause

neuralset==0.0.2 (the pinned version) references exca.steps.base.NoValue in neuralset/events/study.py:

def run(self, value: tp.Any = exca.steps.base.NoValue()) -> tp.Any:

exca exposed NoValue under exca.steps.base (re-exported from exca.steps.backends) up to and including 0.5.25. In 0.5.26 the symbol was moved to exca.steps.identity and the re-export was dropped. Because neuralset==0.0.2 only constrains exca>=0.5.20, a fresh install resolves the latest exca (0.5.26) and fails:

AttributeError: module 'exca.steps.base' has no attribute 'NoValue'
  File ".../neuralset/events/study.py", line 255, in StudyLoader
    def run(self, value: tp.Any = exca.steps.base.NoValue()) -> tp.Any:

tribev2 also imports exca directly (from exca import ConfDict, TaskInfra in main.py and demo_utils.py) without declaring it, so the version it gets is left entirely to transitive resolution.

Change

"neuralset==0.0.2",
"neuraltrain==0.0.2",
# neuralset 0.0.2 references exca.steps.base.NoValue, which exca removed in
# 0.5.26 (moved to exca.steps.identity). Cap exca until neuralset is updated.
"exca>=0.5.20,<0.5.26",

No source changes. Bumping neuralset/neuraltrain to a newer release is not a viable alternative here: every published version after 0.0.2 (0.0.3 through 0.2.2) removes AddText from neuralset.events.transforms, which tribev2/demo_utils.py imports, so a version bump trades this error for an ImportError. Capping exca keeps the code unchanged.

Verification

Reproduced and fixed in a clean Python 3.12 virtualenv.

Before (current main, resolves exca 0.5.26):

$ python -c "from tribev2.demo_utils import TribeModel"
AttributeError: module 'exca.steps.base' has no attribute 'NoValue'

After (this branch, resolves exca 0.5.25):

$ pip show exca | grep Version
Version: 0.5.25
$ python -c "from tribev2.demo_utils import TribeModel; print('IMPORT_OK')"
IMPORT_OK

Note

This is a compatibility cap, not a permanent fix. The cleaner resolution is to publish a neuralset release that targets the current exca API; once that exists, the cap can be relaxed. Until then this restores a working install for everyone.

[idrismunir15]

Thank you very much. This solves the import problems but now produces new errors.