build: Help OpenImageIO find OpenColorIO (#1220)

### Help OpenImageIO find OpenColorIO

### Linked issues
none

### Summarize your change.
Add more hint to allow OpenImageIO to find OpenColorIO. It looks like
OIIO 3.X has changed something that make it more strict.

### Describe the reason for the change.
Builds are failing.

### Describe what you have tested and on which operating system.
CI

### Add a list of changes, and note any that might need special
attention during the review.

### If possible, provide screenshots.

---------

Signed-off-by: Cédrik Fuoco <cedrik.fuoco@autodesk.com>

Author: cedrik-fuoco-adsk

cmake/dependencies/oiio.cmake

@@ -48,8 +48,18 @@ LIST(APPEND _byproducts ${_byprojects_copy})
 # The '_configure_options' list gets reset and initialized in 'RV_CREATE_STANDARD_DEPS_VARIABLES'
 LIST(APPEND _configure_options "-DBUILD_TESTING=OFF")
 LIST(APPEND _configure_options "-DUSE_PYTHON=0") # this on would requireextra pybind11 package
+# OIIO 3.x still calls find_package(Python3) even with USE_PYTHON=0. Point it to our custom Python to prevent finding the system Python (e.g. 3.14 from GitHub
+# runner toolcache).
+LIST(APPEND _configure_options "-DPython3_ROOT_DIR=${RV_DEPS_BASE_DIR}/RV_DEPS_PYTHON3/install")
+LIST(APPEND _configure_options "-DPython3_FIND_STRATEGY=LOCATION")
+LIST(APPEND _configure_options "-DPython3_FIND_REGISTRY=NEVER")
 LIST(APPEND _configure_options "-DUSE_OCIO=ON")
 LIST(APPEND _configure_options "-DOpenColorIO_ROOT=${RV_DEPS_OCIO_ROOT_DIR}")
+IF(RHEL_VERBOSE)
+  LIST(APPEND _configure_options "-DOpenColorIO_DIR=${RV_DEPS_OCIO_ROOT_DIR}/lib64/cmake/OpenColorIO")
+ELSE()
+  LIST(APPEND _configure_options "-DOpenColorIO_DIR=${RV_DEPS_OCIO_ROOT_DIR}/lib/cmake/OpenColorIO")
+ENDIF()
 LIST(APPEND _configure_options "-DUSE_FREETYPE=0")
 LIST(APPEND _configure_options "-DUSE_GIF=OFF")