Update sphinx to 4.5.0 (pvlib#1435)

* bump sphinx and pydata-sphinx-theme versions

* clean up sphinx conf.py

* fix distutils strangeness, maybe

* use freshly-released sphinx==4.5.0

docs/sphinx/source/conf.py

@@ -20,6 +20,9 @@
 # for generating GH links with linenumbers
 import inspect
 
+# import distutils before calling pd.show_versions()
+# https://github.com/pypa/setuptools/issues/3044
+import distutils  # noqa: F401
 import pandas as pd
 pd.show_versions()
 
@@ -244,7 +247,7 @@ def setup(app):
     # In-line links to references as numbers in brackets.
     app.add_css_file("reference_format.css")
     # Add a warning banner at the top of the page if viewing the "latest" docs
-    app.add_javascript("version-alert.js")
+    app.add_js_file("version-alert.js")
 
 # -- Options for LaTeX output ---------------------------------------------
 
@@ -343,8 +346,6 @@ def setup(app):
     'matplotlib': ('https://matplotlib.org/stable', None),
 }
 
-nbsphinx_allow_errors = True
-
 ipython_warning_is_error = False
 
 # suppress "WARNING: Footnote [1] is not referenced." messages

setup.py

@@ -53,8 +53,8 @@
     'optional': ['cython', 'ephem', 'netcdf4', 'nrel-pysam', 'numba',
                  'pvfactors', 'siphon', 'statsmodels',
                  'cftime >= 1.1.1'],
-    'doc': ['ipython', 'matplotlib', 'sphinx == 3.1.2',
-            'pydata-sphinx-theme == 0.8.0', 'sphinx-gallery',
+    'doc': ['ipython', 'matplotlib', 'sphinx == 4.5.0',
+            'pydata-sphinx-theme == 0.8.1', 'sphinx-gallery',
             'docutils == 0.15.2', 'pillow', 'netcdf4', 'siphon',
             'sphinx-toggleprompt >= 0.0.5', 'pvfactors'],
     'test': TESTS_REQUIRE