Revert "Update Circle CI docker image to pytorch 1.6. Closes #1225 (#1322)"

This reverts commit 22ecac6.

Author: vfdev-5

.circleci/config.yml

@@ -4,11 +4,11 @@ parameters:
   pytorch_stable_image:
     type: string
     # https://hub.docker.com/r/pytorch/pytorch/tags
-    default: "pytorch/pytorch:1.6-cuda10.1-cudnn7-runtime"
+    default: "pytorch/pytorch:1.5.1-cuda10.1-cudnn7-runtime"
   pytorch_stable_image_devel:
     type: string
     # https://hub.docker.com/r/pytorch/pytorch/tags
-    default: "pytorch/pytorch:1.6-cuda10.1-cudnn7-devel"
+    default: "pytorch/pytorch:1.5.1-cuda10.1-cudnn7-devel"
   workingdir:
     type: string
     default: "/tmp/ignite"

.github/workflows/pytorch-version-tests.yml

@@ -11,7 +11,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: [3.5, 3.6, 3.7, 3.8]
-        pytorch-version: [1.5.1, 1.4.0, 1.3.1]
+        pytorch-version: [1.4.0, 1.3.1]
         exclude:
           - pytorch-version: 1.3.1
             python-version: 3.8