TOX: Control pip via environment variables

tox.ini

@@ -48,12 +48,6 @@ ARCH =
 [testenv]
 description = Pytest with coverage
 labels = test
-install_command =
-  python -I -m pip install -v \
-  dev: --only-binary numpy,scipy,h5py \
-  !dev: --only-binary numpy,scipy,h5py,pillow,matplotlib \
-  pre,dev: --extra-index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple \
-    {opts} {packages}
 pip_pre =
   pre,dev: true
 pass_env =
@@ -72,6 +66,9 @@ pass_env =
   CLICOLOR_FORCE
 set_env =
   py313: PYTHON_GIL=0
+  dev: PIP_ONLY_BINARY=numpy,scipy,h5py
+  !dev: PIP_ONLY_BINARY=numpy,scipy,h5py,pillow,matplotlib
+  pre,dev: PIP_EXTRA_INDEX_URL=https://pypi.anaconda.org/scientific-python-nightly-wheels/simple
 extras = test
 deps =
   # General minimum dependencies: pin based on API usage
@@ -118,7 +115,6 @@ description = Install and verify import succeeds
 labels = test
 deps =
 extras =
-install_command = python -I -m pip install {opts} {packages}
 commands =
   python -c "import nibabel; print(nibabel.__version__)"