Fix problems with the optional regex requirement

An older version of the regex package with binary "wheel" files for
Python 2.7 is now preferred.  This prevents pip from trying to comp-
ile the package unnecessarily.

setup.py

@@ -115,7 +115,8 @@ def read(*names):
       extras_require={
           "accessibility": [
                             "enum34;python_version<'3.4'",
-                            "regex",
+                            "regex<2022.1.18;python_version<='3.10",
+                            "regex;python_version>'3.10",
                            ],
           "sphinx": [
                      "sphinxwrapper >= 1.2.0",