ci: migrate deprecated grammar (nodejs#2285)

PR-URL: nodejs#2285
Reviewed-By: Richard Lau <[email protected]>

Author: gengjiawen

.github/workflows/tests.yml

@@ -31,9 +31,9 @@ jobs:
           pip install flake8 pytest
       - name: Set Windows environment
         if: matrix.os == 'windows-latest'
-        run:
-          echo '::set-env name=GYP_MSVS_VERSION::2015'
-          echo '::set-env name=GYP_MSVS_OVERRIDE_PATH::C:\\Dummy'
+        run: |
+          echo 'GYP_MSVS_VERSION=2015' >> $Env:GITHUB_ENV
+          echo 'GYP_MSVS_OVERRIDE_PATH=C:\\Dummy' >> $Env:GITHUB_ENV
       - name: Lint Python
         if: matrix.os == 'ubuntu-latest'
         run: |