Clean up old sphinx cruft (#549)

Author: jarrodmillman

numpydoc/numpydoc.py

@@ -31,9 +31,6 @@
 from sphinx.util import logging
 from sphinx.errors import ExtensionError
 
-if sphinx.__version__ < "5":
-    raise RuntimeError("Sphinx 5 or newer is required")
-
 from .docscrape_sphinx import get_doc_object
 from .validate import validate, ERROR_MSGS, get_validation_checks
 from .xref import DEFAULT_LINKS

numpydoc/tests/tinybuild/conf.py

@@ -15,7 +15,6 @@
 autosummary_generate = True
 autodoc_default_options = {"inherited-members": None}
 source_suffix = ".rst"
-master_doc = "index"  # NOTE: will be changed to `root_doc` in sphinx 4
 exclude_patterns = ["_build"]
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),