Allow usage with Python 3.7

Author: samdobson

setup.cfg

@@ -22,6 +22,7 @@ classifiers =
     Programming Language :: Python
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
@@ -30,7 +31,7 @@ classifiers =
 package_dir =
     = src
 packages = find:
-python_requires = >=3.8
+python_requires = >=3.7
 install_requires =
     textual >= 0.1.10