build(deps): restructure docs deps again so not only pip works with extras but poetry as well

pyproject.toml

@@ -31,11 +31,20 @@ h5py = "^3.7.0"
 numpy = "^1.24.1"
 pooch = "^1.6.0"
 tqdm = "^4.64.1"
-ipython = {version = "^8.8.0", optional = true,extras = ["docs"]}
-myst-parser = {version = "^0.18.1", optional = true, extras = ["docs"]}
-nbsphinx = {version = "^0.8.12", optional = true, extras = ["docs"]}
-sphinx = {version = "^5.3.0", optional = true, extras = ["docs"]}
-sphinx-rtd-theme = {version = "^1.1.1", optional = true, extras = ["docs"]}
+ipython = {version = "^8.8.0", optional = true}
+myst-parser = {version = "^0.18.1", optional = true}
+nbsphinx = {version = "^0.8.12", optional = true}
+sphinx = {version = "^5.3.0", optional = true}
+sphinx-rtd-theme = {version = "^1.1.1", optional = true}
+
+[tool.poetry.extras]
+docs = [
+    "ipython",
+    "parser",
+    "nbsphinx",
+    "sphinx",
+    "sphinx-rtd-theme",
+]
 
 [tool.poetry.group.test]
 optional = true