Fixed 403 Error from Wikimedia when reading image

Author: daexs

doc/python/imshow.md

@@ -61,7 +61,13 @@ In order to create a numerical array to be passed to `px.imshow`, you can use a
 ```python
 import plotly.express as px
 from skimage import io
-img = io.imread('https://upload.wikimedia.org/wikipedia/commons/thumb/0/00/Crab_Nebula.jpg/240px-Crab_Nebula.jpg')
+from io import BytesIO
+import requests
+
+url = 'https://upload.wikimedia.org/wikipedia/commons/thumb/0/00/Crab_Nebula.jpg/240px-Crab_Nebula.jpg'
+headers = {"User-Agent": "Mozilla/5.0"}
+response = requests.get(url, headers=headers)
+img = io.imread(BytesIO(response.content))
 fig = px.imshow(img)
 fig.show()
 ```