[CI] Remove support for py3.6 (#1660)

* [CI] Remove support for py3.6

* update

* fix

Author: gaotongxiao

.circleci/test.yml

@@ -145,7 +145,7 @@ workflows:
           name: minimum_version_cpu
           torch: 1.6.0
           torchvision: 0.7.0
-          python: 3.6.9  # The lowest python 3.6.x version available on CircleCI images
+          python: "3.7"
           requires:
             - lint
       - build_cpu:

.github/workflows/merge_stage_test.yml

@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-18.04
     strategy:
       matrix:
-        python-version: [3.6, 3.8, 3.9]
+        python-version: [3.8, 3.9]
         torch: [1.8.1]
         include:
           - torch: 1.8.1