make dask an optional dependency for the dask demo

Author: valeriupredoi

pyproject.toml

@@ -34,7 +34,6 @@ dynamic = [
     "version",
 ]
 dependencies = [
-    "dask!=2024.8.0",  # github.com/dask/dask/issues/11296
     "fsspec",
     "h5netcdf",
     "netcdf4",
@@ -67,6 +66,10 @@ doc = [
     "sphinx",
     "sphinx_rtd_theme",
 ]
+# run dask-demo
+demo = [
+    "dask!=2024.8.0",  # github.com/dask/dask/issues/11296
+]
 # to be added when functionality provided
 # develop = [
 #     "pre-commit",