docs: Update intersphinx_mapping to the current format.

docs/conf.py

@@ -72,22 +72,22 @@
 master_doc = 'index'
 
 # General information about the project.
-project = u'RelStorage'
-copyright = u'2016-2023, RelStorage contributors'
-author = u'RelStorage contributors'
+project = 'RelStorage'
+copyright = '2016-2023, RelStorage contributors'
+author = 'RelStorage contributors'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 
 # The full version, including alpha/beta/rc tags.
-import io
-with io.open('../version.txt') as f:
+
+with open('../version.txt', 'rt', encoding='utf-8') as f:
     release = f.read().strip()
 
 # The short X.Y version.
-version = u'.'.join(release.split('.')[:2])
+version = '.'.join(release.split('.')[:2])
 
 
 # The language for content autogenerated by Sphinx. Refer to documentation
@@ -307,8 +307,8 @@
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-    (master_doc, 'RelStorage.tex', u'RelStorage Documentation',
-     u'RelStorage contributors', 'manual'),
+    (master_doc, 'RelStorage.tex', 'RelStorage Documentation',
+     'RelStorage contributors', 'manual'),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
@@ -343,7 +343,7 @@
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
 man_pages = [
-    (master_doc, 'relstorage', u'RelStorage Documentation',
+    (master_doc, 'relstorage', 'RelStorage Documentation',
      [author], 1)
 ]
 
@@ -358,7 +358,7 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-    (master_doc, 'RelStorage', u'RelStorage Documentation',
+    (master_doc, 'RelStorage', 'RelStorage Documentation',
      author, 'RelStorage', 'One line description of project.',
      'Miscellaneous'),
 ]
@@ -382,20 +382,22 @@
 
 # Example configuration for intersphinx: refer to the Python standard library.
 intersphinx_mapping = {
-    'https://docs.python.org/': None,
-    'http://www.zodb.org/en/latest/': None,
-    'https://zconfig.readthedocs.io/en/latest/': None,
-    'https://zodb-docs.readthedocs.io/en/latest/': None,
-    'https://persistent.readthedocs.io/en/latest/': None,
-    'https://btrees.readthedocs.io/en/latest/': None,
-    'https://transaction.readthedocs.io/en/latest/': None,
-    'https://ntitransactions.readthedocs.io/en/latest/': None,
+    'python': ('https://docs.python.org/', None),
+    'zodb': ('http://www.zodb.org/en/latest/', None),
+    'zconfig': ('https://zconfig.readthedocs.io/en/latest/', None),
+    'zodb2': ('https://zodb-docs.readthedocs.io/en/latest/', None),
+    'persistent': ('https://persistent.readthedocs.io/en/latest/', None),
+    'btrees': ('https://btrees.readthedocs.io/en/latest/', None),
+    'transaction': ('https://transaction.readthedocs.io/en/latest/', None),
+    'ntitransactions': ('https://ntitransactions.readthedocs.io/en/latest/', None)
 }
 
-extlinks = {'issue': ('https://github.com/zodb/relstorage/issues/%s',
-                      'issue #%s'),
-            'pr': ('https://github.com/zodb/relstorage/pull/%s',
-                   'pull request #%s')}
+extlinks = {
+    'issue': ('https://github.com/zodb/relstorage/issues/%s',
+              'issue #%s'),
+    'pr': ('https://github.com/zodb/relstorage/pull/%s',
+           'pull request #%s')
+}
 
 # Sphinx 1.8+ prefers this to `autodoc_default_flags`. It's documented that
 # either True or None mean the same thing as just setting the flag, but