build: For python stub generation, lock pybind11 to pre-3.0 (#4831)

pybind11 3.0 changed the generated stubs, causing CI to fail, so lock
down to no later than the last version before it broke.

We think the pybind11 3.0 generated stubs are mostly better, so at some
point soon, when we have more time to look at it carefully, we will come back
to this topic and bump our wheel workflow to use pybind11 3.0 and update
the stubs accordintly.

Signed-off-by: Larry Gritz <lg@larrygritz.com>

Author: lgritz

pyproject.toml

@@ -49,7 +49,7 @@ oiiotool = "OpenImageIO:_command_line"
 build-backend = "scikit_build_core.build"
 requires = [
     "scikit-build-core>=0.10.6,<1",
-    "pybind11",
+    "pybind11>=2.13,<3",
 ]
 
 [tool.scikit-build]