ci: pin pyproject2conda==0.22.1 to work around 0.23.0 regression (#878)

* ci: pin pyproject2conda==0.22.1 in check-environment-yml

The check-environment-yml job does `pip install pyproject2conda` with no
version constraint, so each CI run grabs the latest release from PyPI.

pyproject2conda 0.23.0 was published on 2026-04-29 and regressed with:

    AttributeError: 'CondaRequirement' object has no attribute 'channel'

raised from `_normalized_requirements._iter_parts` during the call to
`pyproject2conda yaml ...`. This breaks the job for every PR opened
since 2026-04-29, regardless of whether the PR touches pyproject.toml
or environment.yml.

Pin the CI install to v0.22.1 to match the rev already pinned for the
local prek hook in .pre-commit-config.yaml. The two should be bumped
together once a fixed pyproject2conda release is available.

Made-with: Cursor

* ci: widen pyproject2conda pin to >=0.22.1,<0.23

Replaces the strict ==0.22.1 pin with a range pin so a hypothetical
0.22.x patch backport can ship without a workflow edit, while still
excluding the 0.23.x line that broke us.

Also drops the release date from the inline comment (the version
identifier 0.23.0 is the durable reference; git blame recovers the
date) and expands the explanation of the failure mode for future
readers.

Made-with: Cursor

Author: drbenvincent

.github/workflows/ci.yml

@@ -49,7 +49,15 @@ jobs:
         with:
           python-version: "3.12"
       - name: Install pyproject2conda
-        run: pip install pyproject2conda
+        # Pinned to the 0.22.x line to match the local prek hook rev (v0.22.1).
+        # 0.23.0 introduced a regression:
+        # `AttributeError: 'CondaRequirement' object has no attribute 'channel'`
+        # raised from `_iter_parts` during `__hash__` of any conda requirement,
+        # so any invocation that processes conda deps fails immediately.
+        # The upper bound allows a hypothetical 0.22.x patch backport while
+        # excluding 0.23.x. Bump in lockstep with the .pre-commit-config.yaml
+        # rev once a fixed release is available.
+        run: pip install "pyproject2conda>=0.22.1,<0.23"
       - name: Regenerate environment.yml (same args as local prek hook config)
         run: |
           pyproject2conda yaml -e dev -o /tmp/environment.generated.yml -n CausalPy \