[pyproject.toml] Corrected documentation link to stable

pyproject.toml

@@ -41,7 +41,7 @@
     ]
 
 [project.urls]
-    documentation = "https://www.idiap.ch/software/bob/docs/bob/bob.bio.base/master/sphinx/"
+    documentation = "https://www.idiap.ch/software/bob/docs/bob/bob.bio.base/stable/"
     homepage = "https://pypi.org/project/bob.bio.base/"
     repository = "https://gitlab.idiap.ch/bob/bob.bio.base"
     changelog = "https://gitlab.idiap.ch/bob/bob.bio.base/-/releases"