Pin astroid to the latest minor release

This will require a lock step release and update for pylint and astroid
but should minimize the errors that result from an updated astroid
version that has backwards incompatible issues.

pylint/__pkginfo__.py

@@ -29,7 +29,7 @@
 if dev_version is not None:
     version += "-dev" + str(dev_version)
 
-install_requires = ["astroid>=2.3.0,<3", "isort>=4.2.5,<5", "mccabe>=0.6,<0.7"]
+install_requires = ["astroid>=2.3.0,<2.4", "isort>=4.2.5,<5", "mccabe>=0.6,<0.7"]
 
 dependency_links = []  # type: ignore