export tutorials changed in c161138 (#498)

Co-authored-by: dario-coscia <dario-coscia@users.noreply.github.com>

tutorials/tutorial3/tutorial.ipynb

@@ -28,7 +28,7 @@
     "    IN_COLAB = True\n",
     "except:\n",
     "    IN_COLAB = False\n",
-    "if IN_COLAB: \n",
+    "if IN_COLAB:\n",
     "    !pip install \"pina-mathlab\"\n",
     "\n",
     "import torch\n",

tutorials/tutorial3/tutorial.py

@@ -9,7 +9,7 @@
 #
 # First of all, some useful imports.
 
-# In[1]:
+# In[ ]:
 
 
 ## routine needed to run the notebook on Google Colab