Update RtD and Sphinx configuration (#38046)

.github/dependabot.yml

@@ -5,3 +5,8 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
+  # Requirements to build documentation
+  - package-ecosystem: "pip"
+    directory: "/lib/spack/docs"
+    schedule:
+      interval: "daily"

.readthedocs.yml

@@ -1,10 +1,16 @@
 version: 2
 
+build:
+  os: "ubuntu-22.04"
+  apt_packages:
+    - graphviz
+  tools:
+    python: "3.11"
+
 sphinx:
   configuration: lib/spack/docs/conf.py
   fail_on_warning: true
 
 python:
-  version: 3.7
   install:
     - requirements: lib/spack/docs/requirements.txt

lib/spack/docs/_pygments/style.py

@@ -0,0 +1,16 @@
+# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+# The name of the Pygments (syntax highlighting) style to use.
+# We use our own extension of the default style with a few modifications
+from pygments.styles.default import DefaultStyle
+from pygments.token import Generic
+
+
+class SpackStyle(DefaultStyle):
+    styles = DefaultStyle.styles.copy()
+    background_color = "#f4f4f8"
+    styles[Generic.Output] = "#355"
+    styles[Generic.Prompt] = "bold #346ec9"

lib/spack/docs/conf.py

@@ -149,7 +149,6 @@ def setup(sphinx):
 # Get nice vector graphics
 graphviz_output_format = "svg"
 
-
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ["_templates"]
 
@@ -233,30 +232,8 @@ def setup(sphinx):
 # If true, sectionauthor and moduleauthor directives will be shown in the
 # output. They are ignored by default.
 # show_authors = False
-
+sys.path.append("./_pygments")
-# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = "style.SpackStyle"
-# We use our own extension of the default style with a few modifications
-from pygments.style import Style
-from pygments.styles.default import DefaultStyle
-from pygments.token import Comment, Generic, Text
-
-
-class SpackStyle(DefaultStyle):
-    styles = DefaultStyle.styles.copy()
-    background_color = "#f4f4f8"
-    styles[Generic.Output] = "#355"
-    styles[Generic.Prompt] = "bold #346ec9"
-
-
-import pkg_resources
-
-dist = pkg_resources.Distribution(__file__)
-sys.path.append(".")  # make 'conf' module findable
-ep = pkg_resources.EntryPoint.parse("spack = conf:SpackStyle", dist=dist)
-dist._ep_map = {"pygments.styles": {"plugin1": ep}}
-pkg_resources.working_set.add(dist)
-
-pygments_style = "spack"
 
 # A list of ignored prefixes for module index sorting.
 # modindex_common_prefix = []
@@ -341,7 +318,6 @@ class SpackStyle(DefaultStyle):
 # Output file base name for HTML help builder.
 htmlhelp_basename = "Spackdoc"
 
-
 # -- Options for LaTeX output --------------------------------------------------
 
 latex_elements = {

lib/spack/docs/requirements.txt

@@ -1,13 +1,8 @@
-# These dependencies should be installed using pip in order
+sphinx==6.2.1
-# to build the documentation.
+sphinxcontrib-programoutput==0.17
-
+sphinx_design==0.4.1
-sphinx>=3.4,!=4.1.2,!=5.1.0
+sphinx-rtd-theme==1.2.1
-sphinxcontrib-programoutput
+python-levenshtein==0.21.0
-sphinx-design
+docutils==0.18.1
-sphinx-rtd-theme
+pygments==2.15.1
-python-levenshtein
+urllib3==2.0.2
-# Restrict to docutils <0.17 to workaround a list rendering issue in sphinx.
-# https://stackoverflow.com/questions/67542699
-docutils <0.17
-pygments <2.13
-urllib3 <2