[BUG] CI breaks when trying to set env var, updating how env vars are set

[darapuk]

Run echo "::set-env name=PY::$(python -c 'import hashlib, sys;print(hashlib.sha256(sys.version.encode()+sys.executable.encode()).hexdigest())')"
Error: Unable to process command '::set-env name=PY::c19639f9a84382269728f4ed835489e2160195648d7a2fcffd6a3bf36146c743' successfully.
Error: The `set-env` command is disabled. Please upgrade to using Environment Files or opt into unsecure command execution by setting the `ACTIONS_ALLOW_UNSECURE_COMMANDS` environment variable to `true`. For more information see: https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/

[czgu]

Thank you!