CI: Pin to sphinx>=6.2 for docs build on Python 3.13 (#3667)

Fix `ModuleNotFoundError: No module named 'imghdr'` on Python 3.13. Xref sphinx-doc/sphinx#10440 (comment)

* Set needs_sphinx to 6.2

Author: weiji14

.github/workflows/ci_docs.yml

@@ -111,7 +111,7 @@ jobs:
             python-build
             myst-nb
             panel
-            sphinx
+            sphinx>=6.2
             sphinx-autodoc-typehints
             sphinx-copybutton
             sphinx-design

ci/requirements/docs.yml

@@ -26,7 +26,7 @@ dependencies:
     # Dev dependencies (building documentation)
     - myst-nb
     - panel
-    - sphinx
+    - sphinx>=6.2
     - sphinx-autodoc-typehints
     - sphinx-copybutton
     - sphinx-design

doc/conf.py

@@ -171,7 +171,7 @@
 ]
 
 source_suffix = ".rst"
-needs_sphinx = "1.8"
+needs_sphinx = "6.2"
 # Encoding of source files
 source_encoding = "utf-8-sig"
 root_doc = "index"

environment.yml

@@ -37,7 +37,7 @@ dependencies:
     # Dev dependencies (building documentation)
     - myst-nb
     - panel
-    - sphinx
+    - sphinx>=6.2
     - sphinx-autodoc-typehints
     - sphinx-copybutton
     - sphinx-design