Chore: replace deprecated command with environment file

[jongwooo]

Description of your changes

Closes #1302

Update .github/workflows/image.yml to use environment file instead of deprecated set-output command.
For more information, see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

I found the workflow file that use set-output command through the following command:

$ find . -name '*.yml' -o -name '*.yaml' | xargs egrep '\bset-output\b'

AS-IS

echo ::set-output name=VERSION::${VERSION}

echo "::set-output name=git_revision::$(git rev-parse --short HEAD)"

TO-BE

echo "VERSION=${VERSION}" >> $GITHUB_OUTPUT

echo "git_revision=$(git rev-parse --short HEAD)" >> $GITHUB_OUTPUT

I have:

• Read and followed KubeVela's contribution process.
• Update sidebar.js if adding a new page.
• Run yarn start to ensure the changes has taken effect.

Special notes for your reviewer

None