Add Quarto .qmd extension

https://quarto.org/docs/authoring/markdown-basics.html#overview

Author: edgarrmondragon

identify/extensions.py

@@ -229,6 +229,7 @@
     'pyx': {'text', 'cython'},
     'pyz': {'binary', 'pyz'},
     'pyzw': {'binary', 'pyz'},
+    'qmd': {'text', 'quarto'},
     'qml': {'text', 'qml'},
     'r': {'text', 'r'},
     'rake': {'text', 'ruby'},