feat: update extensions.py

Adds `.templ` as an extension as per https://templ.guide/core-concepts/template-generation

Author: dinoshauer

identify/extensions.py

@@ -249,6 +249,7 @@
     'swiftdeps': {'text', 'swiftdeps'},
     'tac': {'text', 'twisted', 'python'},
     'tar': {'binary', 'tar'},
+    'templ': {'text', 'go', 'templ'},
     'tex': {'text', 'tex'},
     'textproto': {'text', 'textproto'},
     'tf': {'text', 'terraform'},