Make CustomHTMLBuilder.default_translator_class a class variable (#476)

ref #475

Author: AA-Turner

sphinx_immaterial/__init__.py

@@ -68,11 +68,17 @@ class CustomHTMLBuilder(base_builder):  # type: ignore
         theme: sphinx.theming.Theme
         templates: sphinx.jinja2glue.BuiltinTemplateLoader
 
-        @property
-        def default_translator_class(self):
-            return html_translator_mixin.get_html_translator(
-                super().default_translator_class
+        if version_info >= (7, 0):
+            default_translator_class = html_translator_mixin.get_html_translator(
+                base_builder.default_translator_class
             )
+        else:
+
+            @property
+            def default_translator_class(self):
+                return html_translator_mixin.get_html_translator(
+                    super().default_translator_class
+                )
 
         def init_js_files(self):
             super().init_js_files()