Get all dependencies from conda

Some notes on this may be useful:
- It was found that specifying `astra-toolbox` as a conda dependency in
  addition to `cupy` was able to make the GPU detectable in the CUDA
  container used in the IRIS CI job. However, the first job was
  sometimes such that the GPU wasn't detected and needed to be rerun,
  but then the second job would have the GPU be detected, for some
  reason.
- Specifying all required packages as conda dependencies somehow got rid
  of the need to rerun the job, where the first job seemingly was
  consistent in having the GPU be detected.

The reason(s) for this behaviour are unknown, but this may be a good
enough workaround to enable `httomo` in the following PR to install
and use `httomo-backends` without issues in the IRIS CI:
DiamondLightSource/httomo#532.

conda/environment.yml

@@ -3,8 +3,13 @@ channels:
   - conda-forge
   - httomo
 dependencies:
-  - conda-forge::cuda-version
+  - conda-forge::astra-toolbox
   - conda-forge::cupy=12.3.0
+  - conda-forge::h5py
+  - conda-forge::imageio
   - conda-forge::numpy<2
+  - conda-forge::nvtx
   - conda-forge::pyyaml
+  - conda-forge::scikit-image
+  - conda-forge::toml
   - conda-forge::tomopy=1.15