v1.15.7.0

Release 1.15.7.0 (7 Sep 2026) -- compared to 1.15.6.0

• ShadingSystem: Query ranked and aggregate post-optimization ShaderGroup compile stats (active_layers, network_depth, texture_ops, noise_ops) through new system getattribute keys. #2147 (1.15.7.0, 1.14.12.0) (by @lgritz / Larry Gritz)
• python: The OSLQuery Python bindings no longer require the OpenImageIO Python types: a new OSLQuery.Parameter.type_name property returns the parameter's type as a string, and the OpenImageIO module is no longer force-imported at startup. This lets Python programs use OSLQuery alongside an OpenImageIO built against a different binding library (pybind11 vs nanobind). #2142 (by @lgritz / Larry Gritz)
• testrender: Fix discontinuities in principal directions by switching to a more robust method of building an orthonormal basis from a normal. #2154 (by @AlexeySmolenchuk / Alexey Smolenchuk)
• fix: Repair unsafe string formatting of certain errors (a plain error message that happened to contain brace characters could confuse the formatting engine). #2145 (1.15.7.0, 1.14.12.0) (by @lgritz / Larry Gritz)
• build: Support LLVM 23. #2159 (1.15.7.0, 1.14.12.0) (by @lgritz / Larry Gritz)
• build: Correctly serialize the CUDA build of testrender. #2157 (by @jfpanisset / Jean-Francois Panisset) (1.15.7.0, 1.14.12.0)
• ci: Update all GitHub Actions to their latest versions. #2144 (by @lgritz / Larry Gritz)
• ci: Fix broken CI caused by a recent OIIO change and a libtiff vs webp conflict. #2160 (1.15.7.0, 1.14.12.0) (by @lgritz / Larry Gritz)