Support jinja2-3.0

Since jinja2-3.0, some utility functions like contextfunction and
environmentfilter are renamed to new name.  This follows the updates to
support jinja2-3.0 or above.

sphinx/jinja2glue.py

@@ -12,7 +12,7 @@
 from pprint import pformat
 from typing import TYPE_CHECKING, Any, Callable, Dict, Iterator, List, Tuple, Union
 
-from jinja2 import BaseLoader, FileSystemLoader, TemplateNotFound, contextfunction
+from jinja2 import BaseLoader, FileSystemLoader, TemplateNotFound
 from jinja2.environment import Environment
 from jinja2.sandbox import SandboxedEnvironment
 from jinja2.utils import open_if_exists
@@ -22,6 +22,11 @@
 from sphinx.util import logging
 from sphinx.util.osutil import mtimes_of_files
 
+try:
+    from jinja2.utils import pass_context  # type: ignore # jinja2-3.0 or above
+except ImportError:
+    from jinja2 import contextfunction as pass_context
+
 if TYPE_CHECKING:
     from sphinx.builders import Builder
 
@@ -101,7 +106,7 @@ def __next__(self) -> int:
     next = __next__  # Python 2/Jinja compatibility
 
 
-@contextfunction
+@pass_context
 def warning(context: Dict, message: str, *args: Any, **kwargs: Any) -> str:
     if 'pagename' in context:
         filename = context.get('pagename') + context.get('file_suffix', '')
@@ -180,9 +185,9 @@ def init(self, builder: "Builder", theme: Theme = None, dirs: List[str] = None)
         self.environment.filters['toint'] = _toint
         self.environment.filters['todim'] = _todim
         self.environment.filters['slice_index'] = _slice_index
-        self.environment.globals['debug'] = contextfunction(pformat)
+        self.environment.globals['debug'] = pass_context(pformat)
         self.environment.globals['warning'] = warning
-        self.environment.globals['accesskey'] = contextfunction(accesskey)
+        self.environment.globals['accesskey'] = pass_context(accesskey)
         self.environment.globals['idgen'] = idgen
         if use_i18n:
             self.environment.install_gettext_translations(builder.app.translator)

sphinx/util/rst.py

@@ -18,11 +18,17 @@
 from docutils.parsers.rst.languages import en as english
 from docutils.statemachine import StringList
 from docutils.utils import Reporter
-from jinja2 import Environment, environmentfilter
+from jinja2 import Environment
 
 from sphinx.locale import __
 from sphinx.util import docutils, logging
 
+try:
+    from jinja2.utils import pass_environment  # type: ignore  # jinja2-3.0 or above
+except ImportError:
+    from jinja2 import environmentfilter as pass_environment
+
+
 logger = logging.getLogger(__name__)
 
 docinfo_re = re.compile(':\\w+:.*?')
@@ -51,7 +57,7 @@ def charwidth(char: str, widechars: str) -> int:
     return sum(charwidth(c, widechars) for c in text)
 
 
-@environmentfilter
+@pass_environment
 def heading(env: Environment, text: str, level: int = 1) -> str:
     """Create a heading for *level*."""
     assert level <= 3