Replace std::sync::Mutex with parking_lot::Mutex in languages/src/python.rs (#29889)

This appears to be the only place `std::sync::Mutex` is used, Zed always
prefers `parking_lot`.

Release Notes:

- N/A

crates/languages/Cargo.toml

@@ -46,6 +46,7 @@ language.workspace = true
 log.workspace = true
 lsp.workspace = true
 node_runtime.workspace = true
+parking_lot.workspace = true
 paths.workspace = true
 pet-conda.workspace = true
 pet-core.workspace = true