Drop numpy as a dependency

noxfile.py

@@ -29,8 +29,7 @@ def test(session: nox.Session) -> None:
 @nox.session(name="test-cli")
 def test_cli(session: nox.Session) -> None:
     """Test the command line interface."""
-    session.install("-r", "requirements/requires.txt")
-    session.install(".", "--no-deps")
+    session.install(".")
     session.run("bmi-render", "--help")
     session.run("bmi-render", "--version")
 

pyproject.toml

@@ -30,15 +30,16 @@ classifiers = [
     "Topic :: Scientific/Engineering :: Physics",
 ]
 dependencies = [
-    "numpy",
 ]
 dynamic = [
     "readme",
 ]
 
 [project.optional-dependencies]
+dev = ["nox"]
 testing = [
   "coverage",
+  "numpy",
   "pytest",
 ]
 

src/bmipy/bmi.py

@@ -8,10 +8,12 @@
 
 from abc import ABC
 from abc import abstractmethod
+from typing import TYPE_CHECKING
 from typing import Any
 
-import numpy as np
-from numpy.typing import NDArray
+if TYPE_CHECKING:
+    import numpy as np
+    from numpy.typing import NDArray
 
 
 class Bmi(ABC):