Revert blocking of Black 24.2 upgrade

setup.cfg

@@ -27,7 +27,7 @@ package_dir =
 packages = find:
 install_requires =
     # NOTE: remember to keep `constraints-oldest.txt` in sync with these
-    black>=21.5b1,<24.2  # upper limit until incompatibility fixed
+    black>=21.5b1
     darkgraylib @ git+https://github.com/akaihola/darkgraylib.git@main
     graylint @ git+https://github.com/akaihola/graylint.git@main
     toml>=0.10.0
@@ -52,7 +52,7 @@ color =
 test =
     # NOTE: remember to keep `constraints-oldest.txt` in sync with these
     airium>=0.2.3
-    black>=21.7b1,<24.2  # prevent Mypy error about `gen_python_files`, see issue #189
+    black>=21.7b1  # to prevent Mypy error about `gen_python_files`, see issue #189
     cryptography>=3.3.2  # through twine, fixes CVE-2020-36242
     defusedxml>=0.7.1
     flynt>=0.76,<0.78