chore(deps): update dependency backrefs to v5.9 (#314)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

docs/user-guide/requirements/requirements.txt

@@ -10,13 +10,14 @@ babel==2.17.0 \
     # via
     #   mkdocs-git-revision-date-localized-plugin
     #   mkdocs-material
-backrefs==5.8 \
-    --hash=sha256:2cab642a205ce966af3dd4b38ee36009b31fa9502a35fd61d59ccc116e40a6bd \
-    --hash=sha256:2e1c15e4af0e12e45c8701bd5da0902d326b2e200cafcd25e49d9f06d44bb61b \
-    --hash=sha256:a66851e4533fb5b371aa0628e1fee1af05135616b86140c9d787a2ffdf4b8fdc \
-    --hash=sha256:bbef7169a33811080d67cdf1538c8289f76f0942ff971222a16034da88a73486 \
-    --hash=sha256:c67f6638a34a5b8730812f5101376f9d41dc38c43f1fdc35cb54700f6ed4465d \
-    --hash=sha256:e3a63b073867dbefd0536425f43db618578528e3896fb77be7141328642a1585
+backrefs==5.9 \
+    --hash=sha256:6907635edebbe9b2dc3de3a2befff44d74f30a4562adbb8b36f21252ea19c5cf \
+    --hash=sha256:7fdf9771f63e6028d7fee7e0c497c81abda597ea45d6b8f89e8ad76994f5befa \
+    --hash=sha256:808548cb708d66b82ee231f962cb36faaf4f2baab032f2fbb783e9c2fdddaa59 \
+    --hash=sha256:cc37b19fa219e93ff825ed1fed8879e47b4d89aa7a1884860e2db64ccd7c676b \
+    --hash=sha256:db8e8ba0e9de81fcd635f440deab5ae5f2591b54ac1ebe0550a2ca063488cd9f \
+    --hash=sha256:df5e169836cc8acb5e440ebae9aad4bf9d15e226d3bad049cf3f6a5c20cc8dc9 \
+    --hash=sha256:f48ee18f6252b8f5777a22a00a09a85de0ca931658f1dd96d4406a34f3748c60
     # via mkdocs-material
 certifi==2025.6.15 \
     --hash=sha256:2e0c7ce7cb5d8f8634ca55d2ba7e6ec2689a2fd6537d8dec1296a477a4910057 \