specify biopython==1.81 version while installing (sokrypton#622)

Author: sid-betalol

beta/omegafold.ipynb

@@ -62,7 +62,7 @@
         "    if not os.path.isdir(\"OmegaFold\"):\n",
         "      %shell git clone --branch beta --quiet https://github.com/sokrypton/OmegaFold.git\n",
         "      # %shell cd OmegaFold; pip -q install -r requirements.txt\n",
-        "      %shell pip -q install py3Dmol biopython\n",
+        "      %shell pip -q install py3Dmol biopython==1.81\n",
         "      %shell apt-get install aria2 -qq > /dev/null\n",
         "      %shell aria2c -q -x 16 https://helixon.s3.amazonaws.com/release1.pt\n",
         "      %shell mkdir -p ~/.cache/omegafold_ckpt\n",
@@ -236,4 +236,4 @@
       "outputs": []
     }
   ]
-}
+}