Add llvmlite as a numba dependency

Even though llvmlite is a dependency of numba, we explicitly import it,
so for us it should count as a direct dependency.

pyproject.toml

@@ -78,7 +78,7 @@ tests = [
 ]
 rtd = ["sphinx>=5.1.0,<6", "pygments", "pydot", "pydot2", "pydot-ng"]
 jax = ["jax", "jaxlib"]
-numba = ["numba>=0.57"]
+numba = ["numba>=0.57", "llvmlite"]
 
 [tool.setuptools.packages.find]
 include = ["pytensor*"]