using collection names with spaces in them breaks tcia_dataset.ipynb

Describe the bug
In the "Create TciaDataset" step of the notebook if you enter a collection with spaces (e.g. "Lung Phantom") into the collection variable it produces an error. Here is the relevant part of the code:

Let's take the "QIN-PROSTATE-Repeatability" collection for example

collection, seg_type = "QIN-PROSTATE-Repeatability", "SEG"

Here is the error:

KeyError Traceback (most recent call last)
in
5 transform = Compose(
6 [
----> 7 LoadImaged(reader="PydicomReader", keys=["image", "seg"], label_dict=TCIA_LABEL_DICT[collection]),
8 ]
9 )

KeyError: 'Lung Phantom'

Environment (please complete the following information):
I was working on Google Colab

tcia_dataset.ipynb の「Create TciaDataset」ステップから始め、TCIA_LABEL_DICT[collection] と LoadImaged の設定を調べます。Google Colab で「Lung Phantom」コレクションを使って失敗を再現します。完了条件は、ノートブックがスペースを含むコレクション名を KeyError を発生させずに受け入れることです。