fix(docker): pin dockerfile's gradient-sdk version to 1.5.0

Author: Roger Lam

Dockerfile

@@ -1,7 +1,7 @@
 FROM python:3.8
 
 RUN pip install --no-cache-dir --upgrade pip && \
-    pip install --no-cache-dir gradient
+    pip install --no-cache-dir gradient==1.5.0
 
 ENV PAPERSPACE_API_KEY your_api_key_value
 ENV PAPERSPACE_WEB_URL https://console.paperspace.com