add get_a_talk func

app.py

@@ -204,6 +204,16 @@ def generate_talk_with_audio(input, avatar_url, api_key = did_api_key):
     response = requests.post(url, json=payload, headers=headers)
     return response.json()
 
+
+def get_a_talk(id, api_key = os.environ.get('DID_API_KEY')):
+    url = "https://api.d-id.com/talks/" + id
+    headers = {
+        "accept": "application/json",
+        "authorization": "Basic "+api_key
+    }
+    response = requests.get(url, headers=headers)
+    return response.json()
+
 def get_mp4_video(input, avatar_url=avatar_url):
     response = generate_talk_with_audio(input=input, avatar_url=avatar_url)
     talk = get_a_talk(response['id'])