Fix initializer list order

[tmartin-gh]

When matx.h is included in a .cpp file and libnvtiff is present on the system, there is an initializer list ordering error during compilation:

In file included from /build/_deps/matx-src/include/matx/file_io/file_io.h:50,
                 from /build/_deps/matx-src/include/matx.h:44,
                 from /workspace/src/test.cpp:2:
/build/_deps/matx-src/include/matx/file_io/tiff.h: In constructor 'matx::io::Tiff::Tiff(cudaStream_t, int)':
/build/_deps/matx-src/include/matx/file_io/tiff.h:135:22: error: 'matx::io::Tiff::stream_' will be initialized after [-Werror=reorder]
  135 |         cudaStream_t stream_;
      |                      ^~~~~~~
/build/_deps/matx-src/include/matx/file_io/tiff.h:133:13: error:   'int matx::io::Tiff::NUM_DECODERS_' [-Werror=reorder]
  133 |         int NUM_DECODERS_;
      |             ^~~~~~~~~~~~~
/build/_deps/matx-src/include/matx/file_io/tiff.h:53:9: error:   when initialized here [-Werror=reorder]
   53 |         Tiff(cudaStream_t stream=0, int NUM_DECODERS=1)
      |         ^~~~

This PR fixes the issue

[tmartin-gh]

/build

[coveralls]

coverage: 93.143% (-0.07%) from 93.209%
when pulling 7da0de0 on tmartin-gh:tjm/tiff_warning
into 4f84363 on NVIDIA:main.