Update Imath to version 3.1.11 / rev 6 via SR 1184838
    
    https://build.opensuse.org/request/show/1184838
    by user pgajdos + anag+factory
    - update to 3.1.11:
      * Fix a problem where downstream projects using Imath would build
        python bindings even if they weren't requested.
      * Fix for missing `std::bit_cast`
      * Fix missing/necessary use of IMATH_HOSTDEVICE
      * IMATH_INSTALL_PKG_CONFIG is now on by default, even on Windows
      * Fix calling default constructor by uniform init in TypeTraits
      * Fix redundant PYIMATH_EXPORTS causing compile issues on
        Windows Clang
      * Update to SO versioning policy:
      * succ()/pred() now use std::nextafter().
      * Expand epsilon bounds for m44x pyImath test.
      * Rename "docs" to "website".
      * Add missing copyright/license identifiers.
    
      * Fix formatting in release notes
    - initial version 3.0.1, splitted from openexr (forwarded request 1184362 from dirkmueller)