build(tox): install the in-tree smmap and gitdb

Since 8a08afa (gitpython-developers#2179), `smmap` and `gitdb` are developed in this
repository, and CI installs them from there, together with GitPython,
with `pip install ./smmap ./gitdb ".[${EXTRAS}]"`. tox
did not follow: its environments install GitPython's wheel, and pip
fetches `gitdb` and `smmap` from PyPI to satisfy its `gitdb>=4.0.1,<5`
requirement. So `tox` could test GitPython against different `gitdb`
and `smmap` code than CI does, for example after a change to them
that has not been released yet.

Add the two directories to `deps` in `[tool.tox.env_run_base]`, as
`{tox_root}/smmap` and `{tox_root}/gitdb`. tox installs `deps` before
the package's own dependencies, which they then satisfy, so pip keeps
them. Every environment that installs GitPython inherits this. `ruff`,
`format`, and `misc` set their own `deps` and skip installing
GitPython, so they are unaffected.

As with other `deps`, tox does not notice changes inside those
directories, so an existing environment needs `tox -r` to pick up
edits to `smmap` or `gitdb`.

Checked with tox 4.22.0 and 4.67.1. `tox config` shows the two paths
in the `deps` of `py39`, `py313`, `mypy`, `html`, and `gix`, and not
`ruff`. The `py39` smoke check and `html` passed, and
`tox -e py313 -- --collect-only -q test/test_util.py` collected the
tests. In each of those environments, `smmap` 5.0.3 and `gitdb` 4.0.12
came from the local directories, per their `direct_url.json`.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: EliahKagan

pyproject.toml

@@ -179,6 +179,8 @@ env_list = [
 [tool.tox.env_run_base]
 description = "Run unit tests"
 package = "wheel"
+# Use the in-tree smmap and gitdb, as CI does, rather than releases from PyPI.
+deps = ["{tox_root}/smmap", "{tox_root}/gitdb"]
 extras = ["test"]
 pass_env = [
     "SSH_*",