Add sphinx-redirect extension (#3406)

*   Added `sphinx_redirects` to the project dependencies
*   Created `redirects.py` with URL mapping for redirected pages
*   Updated `conf.py` to import `redirect.py` and use the sphinx_redirects extension
*   Added redirects for recently deleted tutorials: `intermediate/flask_rest_api_tutorial`, `beginner/ptcheat.html`, `beginner/deploy_seq2seq_hybrid_frontend_tutorial.html` to redirect to ../index.html.

Author: svekars

.ci/docker/requirements.txt

@@ -1,9 +1,10 @@
 # --extra-index-url https://download.pytorch.org/whl/cu117/index.html # Use this to run/publish tutorials against the latest binaries during the RC stage. Comment out after the release. Each release verify the correct cuda version.
 # Refer to ./jenkins/build.sh for tutorial build instructions
 
-sphinx==5.0.0
+sphinx==5.3.0
 sphinx-gallery==0.11.1
-sphinx_design
+sphinx-reredirects==0.1.4
+sphinx-design==0.4.0
 docutils==0.16
 sphinx-copybutton
 sphinx_sitemap==2.6.0

conf.py

@@ -45,7 +45,7 @@
 import plotly.io as pio
 from pathlib import Path
 pio.renderers.default = 'sphinx_gallery'
-
+from redirects import redirects
 
 import sphinx_gallery.gen_rst
 import multiprocessing
@@ -121,7 +121,8 @@ def wrapper(*args, **kwargs):
     'sphinx_copybutton',
     'sphinx_gallery.gen_gallery',
     'sphinx_design',
-    'sphinx_sitemap'
+    'sphinx_sitemap',
+    'sphinx_reredirects'
 ]
 
 intersphinx_mapping = {

redirects.py

@@ -0,0 +1,5 @@
+redirects = {
+    "intermediate/flask_rest_api_tutorial": "../index.html",
+    "beginner/ptcheat.html": "../index.html",
+    "beginner/deploy_seq2seq_hybrid_frontend_tutorial.html": "../index.html",
+}