[CI] Add missing dependencies for notebooks in Azure pipeline steps (giotto-ai#643)

* Install nbformat in wheel testing step for manylinux2014 jobs

* Ensure X is returned as a numpy array in MNIST_classification notebook

* Use Python 3.7-compatible f-strings

* [CI] Install umap-learn and gensim in notebooks step

Author: ulupo

azure-pipelines.yml

@@ -70,6 +70,8 @@ jobs:
   - script: |
       set -e
       python -m pip install pandas pytest pytest-cov pytest-azurepipelines pytest-benchmark hypothesis
+  # nbformat is needed by plotly: https://github.com/plotly/plotly.py/issues/2159
+      python -m pip install nbformat
       mkdir tmp_test_cov
       cd tmp_test_cov
       pytest --pyargs gtda --ignore-glob='*externals*' --no-cov --no-coverage-upload
@@ -78,7 +80,7 @@ jobs:
 
   - script: |
       set -e
-      python -m pip install openml matplotlib
+      python -m pip install openml matplotlib umap-learn gensim
       python -m pip install papermill
       cd examples
       for n in *.ipynb

examples/MNIST_classification.ipynb

@@ -46,7 +46,7 @@
    "source": [
     "from sklearn.datasets import fetch_openml\n",
     "\n",
-    "X, y = fetch_openml(\"mnist_784\", version=1, return_X_y=True)"
+    "X, y = fetch_openml(\"mnist_784\", version=1, return_X_y=True, as_frame=False)"
    ]
   },
   {
@@ -614,21 +614,9 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
-  },
-  "language_info": {
-   "codemirror_mode": {
-    "name": "ipython",
-    "version": 3
-   },
-   "file_extension": ".py",
-   "mimetype": "text/x-python",
-   "name": "python",
-   "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython3",
-   "version": "3.8.5"
   }
  },
  "nbformat": 4,

examples/local_hom_NLP_disambiguation.ipynb

@@ -171,10 +171,10 @@
    "outputs": [],
    "source": [
     "print(f\"\"\"Example of a preprocessed sentence where 'note' is used as a verb:\n",
-    "{refined_list[0] = }\n",
+    "refined_list[0] = {refined_list[0]}\n",
     "\n",
     "Example of preprocessed sentence where 'note' refers to music:\n",
-    "{refined_list[1] = }\"\"\")"
+    "refined_list[1] = {refined_list[1]}\"\"\")"
    ]
   },
   {