Update dependency diffusers to v0.26.3 (#256)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

pyproject.toml

@@ -41,7 +41,7 @@ dependencies = [
     # MANDATORY for cneuromax/fitting/deeplearning/
     "lightning==2.2.0.post0",
     # OPTIONAL for cneuromax/fitting/deeplearning/
-    "diffusers==0.26.2", # Diffusion models
+    "diffusers==0.26.3", # Diffusion models
     "transformers==4.37.2", # HuggingFace models & utils
     "datasets==2.17.0", # HuggingFace datasets
     # MANDATORY for cneuromax/fitting/neuroevolution/