Treat `.postcss` files as CSS (#19416)

Marshall Bowers created

This PR makes it so `.postcss` files are recognized as CSS.

The `tree-sitter-css` grammar has basic support for PostCSS:
https://github.com/tree-sitter/tree-sitter-css/issues/17#issuecomment-1830349808.

Closes #18051.

Release Notes:

- `.postcss` files are now recognized as CSS.

Change summary

assets/icons/file_icons/file_types.json | 1 +
crates/languages/src/css/config.toml    | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)

Detailed changes

crates/languages/src/css/config.toml 🔗

@@ -1,6 +1,6 @@
 name = "CSS"
 grammar = "css"
-path_suffixes = ["css"]
+path_suffixes = ["css", "postcss"]
 autoclose_before = ";:.,=}])>"
 brackets = [
     { start = "{", end = "}", close = true, newline = true },