fix: handle reset() return in ColorConfig constructor

OIIO_NODISCARD_ERROR added to ColorConfig::reset() in color.h requires
updating ColorConfig constructor to use the return value.

Add a cast (void) to explicitly discard the return from reset().
The error still remains queryable via has_error().

Signed-off-by: Luna Kim <177369799+luna-y-kim@users.noreply.github.com>

Author: luna-y-kim

src/libOpenImageIO/color_ocio.cpp

@@ -807,7 +807,7 @@ ColorConfig::Impl::IdentifyBuiltinColorSpace(const char* name) const
 
 
 
-ColorConfig::ColorConfig(string_view filename) { reset(filename); }
+ColorConfig::ColorConfig(string_view filename) { (void)reset(filename); }