feat: add role-specific config (#42)

Now we can set role temperature. For example:

```
- name: shell
  prompt: >
    I want you to act as a linux shell expert.
    I want you to answer only with bash code.
    Do not write explanations.
  temperature: 0.4
```

1 files changed, 1 insertions, 1 deletions

diff --git a/src/client.rs b/src/client.rs
index 862fa0e..6d01109 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -148,7 +148,7 @@ impl ChatGptClient {
             "messages": messages,
         });
 
-        if let Some(v) = self.config.borrow().temperature {
+        if let Some(v) = self.config.borrow().get_temperature() {
             body.as_object_mut()
                 .and_then(|m| m.insert("temperature".into(), json!(v)));
         }