🔧 MAINTAIN: Remove upper bound from Python version constraint (#40)

Author: cjolowicz

setup.cfg

@@ -30,7 +30,7 @@ project_urls =
 packages = find:
 install_requires =
     markdown-it-py>=1.0.0,<3.0.0
-python_requires = ~=3.6
+python_requires = >=3.6
 include_package_data = True
 zip_safe = True
 
@@ -48,7 +48,7 @@ testing =
     pytest-cov
     pytest-regressions
 rtd =
-    myst-parser~=0.14.0
+    myst-parser~=0.16.1
     sphinx-book-theme~=0.1.0
 
 [mypy]