Move @import to [[theme.stylesheets]]

Author: AA-Turner

python_docs_theme/static/pydoctheme.css

@@ -1,5 +1,3 @@
-@import url('classic.css');
-
 /* Common colours */
 :root {
     --good-color: rgb(41 100 51);

python_docs_theme/theme.toml

@@ -1,6 +1,7 @@
 [theme]
 inherit = "default"
 stylesheets = [
+    "classic.css",
     "pydoctheme.css",
 ]
 pygments_style = { default = "default", dark = "monokai" }