chore(deps): bump allenevans/set-env from 2.2.0 to 3.0.0 (#782)

Bumps [allenevans/set-env](https://github.com/allenevans/set-env) from 2.2.0 to 3.0.0.
- [Release notes](https://github.com/allenevans/set-env/releases)
- [Changelog](https://github.com/allenevans/set-env/blob/master/CHANGELOG.md)
- [Commits](allenevans/set-env@v2.2.0...v3.0.0)

---
updated-dependencies:
- dependency-name: allenevans/set-env
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/backstop.yml

@@ -28,7 +28,7 @@ jobs:
           site_name: idrc
           max_timeout: 300
       - name: Set environment variables
-        uses: allenevans/set-env@v2.2.0
+        uses: allenevans/set-env@v3.0.0
         with:
           BASE_URL: ${{ steps.netlify.outputs.url }}
       - name: Install dependencies, generate reference images, run visual regression tests