Update main.yml

actions/checkout@v2 -> actions/checkout@v3

Author: mikaem

.github/workflows/main.yml

@@ -9,11 +9,11 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest]
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: [3.7, 3.8, 3.9, 3.10]
     name: Python ${{ matrix.python-version }} example
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - run: git fetch --depth=1 origin +refs/tags/*:refs/tags/*
     - name: setup-conda
       uses: s-weigand/setup-conda@v1