Get rid of Cuda texture warning

When JIT compiling the backprojection kernel with Cuda >= 11.7, the following warnings appear:

/cvmfs/tomo.esrf.fr/software/packages/linux/x86_64/tomotools/2024_03_27/lib/python3.11/site-packages/nabu/cuda/kernel.py:49: UserWarning: The CUDA compiler succeeded, but said the following:
kernel.cu(228): warning #177-D: variable "x_stop_other" was declared but never referenced

kernel.cu(230): warning #177-D: variable "y_stop_other" was declared but never referenced


  self.module = SourceModule(self.src, **self.sourcemodule_kwargs)
/cvmfs/tomo.esrf.fr/software/packages/linux/x86_64/tomotools/2024_03_27/lib/python3.11/site-packages/nabu/cuda/kernel.py:49: UserWarning: The CUDA compiler succeeded, but said the following:
kernel.cu(228): warning #177-D: variable "x_stop_other" was declared but never referenced

kernel.cu(230): warning #177-D: variable "y_stop_other" was declared but never referenced

  self.module = SourceModule(self.src, **self.sourcemodule_kwargs)
/cvmfs/tomo.esrf.fr/software/packages/linux/x86_64/tomotools/2024_03_27/lib/python3.11/site-packages/nabu/cuda/kernel.py:49: UserWarning: The CUDA compiler succeeded, but said the following:
kernel.cu(131): warning #1215-D: function "tex2D(texture<T, 2, cudaReadModeElementType>, float, float) [with T=float]"
/cvmfs/hpc.esrf.fr/software/packages/ubuntu20.04/x86_64/cuda/11.7.1/bin/../targets/x86_64-linux/include/texture_fetch_functions.h(198): here was declared deprecated

kernel.cu(132): warning #1215-D: function "tex2D(texture<T, 2, cudaReadModeElementType>, float, float) [with T=float]"
/cvmfs/hpc.esrf.fr/software/packages/ubuntu20.04/x86_64/cuda/11.7.1/bin/../targets/x86_64-linux/include/texture_fetch_functions.h(198): here was declared deprecated

kernel.cu(133): warning #1215-D: function "tex2D(texture<T, 2, cudaReadModeElementType>, float, float) [with T=float]"
/cvmfs/hpc.esrf.fr/software/packages/ubuntu20.04/x86_64/cuda/11.7.1/bin/../targets/x86_64-linux/include/texture_fetch_functions.h(198): here was declared deprecated

kernel.cu(134): warning #1215-D: function "tex2D(texture<T, 2, cudaReadModeElementType>, float, float) [with T=float]"
/cvmfs/hpc.esrf.fr/software/packages/ubuntu20.04/x86_64/cuda/11.7.1/bin/../targets/x86_64-linux/include/texture_fetch_functions.h(198): here was declared deprecated

kernel.cu(21): warning #177-D: function "linear_interpolation" was declared but never referenced

This list of warnings is scary for users.
Backprojector is ready for cuda 12 so this warning can be removed.