Upgrade tree-sitter-php to v0.21.1 (#6902)

This PR upgrades `tree-sitter-php` to v0.21.1.

Here is the diff between our current version and this version:
d43130fd15...29a49d3a53

The primary impetus for this change is to get this change that adds the
`license` field to the `Cargo.toml`:
https://github.com/tree-sitter/tree-sitter-php/pull/193

This will silence the warning that is shown when running
`script/generate-licenses`.

Release Notes:

- Upgraded `tree-sitter-php` to v0.21.1.

crates/zed/src/languages.rs

@@ -251,7 +251,7 @@ pub fn init(
     );
     language(
         "php",
-        tree_sitter_php::language(),
+        tree_sitter_php::language_php(),
         vec![
             Arc::new(php::IntelephenseLspAdapter::new(node_runtime.clone())),
             Arc::new(tailwind::TailwindLspAdapter::new(node_runtime.clone())),