fix(cmake): hide a warning when building the tests standalone

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

Author: henryiii

tests/pyproject.toml

@@ -10,6 +10,10 @@ name = "pybind11_tests"
 version = "0.0.1"
 dependencies = ["pytest", "pytest-timeout", "numpy", "scipy"]
 
+[tool.scikit-build]
+# Hide a warning while we also support CMake < 3.15
+cmake.version = ">=3.15"
+
 [tool.scikit-build.cmake.define]
 PYBIND11_FINDPYTHON = true