chore: clear cache when there's no active requests

crates/llama-cpp-bindings/llama.cpp

@@ -1 +1 @@
-Subproject commit 638ff1aba1fa200f0bdc0ee3709176ddd783a49d
+Subproject commit f858db8db3a98968ad3764c409e43e44c443079b

crates/llama-cpp-bindings/src/engine.cc

@@ -100,6 +100,7 @@ class TextInferenceEngineImpl : public TextInferenceEngine {
     stopped_requests_.clear();
 
     if (requests_.size() == 0) {
+      llama_kv_cache_clear(ctx);
       return {};
     }