Change transformers version assert (#472)

setup.cfg

@@ -36,7 +36,7 @@ install_requires =
     accelerate>=0.20.3,<0.21.0
     huggingface-hub>=0.11.1,<1.0.0
     tokenizers>=0.13.3
-    transformers>=4.32.0
+    transformers>=4.31.0,<5.0.0  # if you change this, please also change version assert in petals/__init__.py
     speedtest-cli==2.1.3
     pydantic>=1.10,<2.0  # 2.0 is incompatible with hivemind yet
     hivemind==1.1.9