Migrate env variable setting (#113)

Author: jirikuncar

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Install pre-commit
       run: python -m pip install pre-commit
     - name: set PY
-      run: echo "::set-env name=PY::$(python -c 'import hashlib, sys;print(hashlib.sha256(sys.version.encode()+sys.executable.encode()).hexdigest())')"
+      run: echo "PY=$(python -c 'import hashlib, sys;print(hashlib.sha256(sys.version.encode()+sys.executable.encode()).hexdigest())')" >> $GITHUB_ENV
     - uses: actions/cache@v1
       with:
         path: ~/.cache/pre-commit