chore(deps): bump crazy-max/ghaction-import-gpg from 5 to 6

Bumps [crazy-max/ghaction-import-gpg](https://github.com/crazy-max/ghaction-import-gpg) from 5 to 6.
- [Release notes](https://github.com/crazy-max/ghaction-import-gpg/releases)
- [Commits](crazy-max/ghaction-import-gpg@v5...v6)

---
updated-dependencies:
- dependency-name: crazy-max/ghaction-import-gpg
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/cron-update-rust.yml

@@ -15,7 +15,7 @@ jobs:
         with:
           app_id: ${{ secrets.APP_ID }}
           private_key: ${{ secrets.APP_PRIVATE_KEY }}
-      - uses: crazy-max/ghaction-import-gpg@v5
+      - uses: crazy-max/ghaction-import-gpg@v6
         with:
           gpg_private_key: ${{ secrets.GPG_PRIVATE_KEY }}
           git_user_signingkey: true