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](https://github.com/crazy-max/ghaction-import-gpg/compare/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] <support@github.com>

.github/workflows/build.yml

@@ -739,7 +739,7 @@ jobs:
       - name: Delete build directory
         run: rm -rf build
       - name: Import Ubuntu PPA GPG private key
-        uses: crazy-max/ghaction-import-gpg@v5
+        uses: crazy-max/ghaction-import-gpg@v6
         with:
           gpg_private_key: ${{secrets.UBUNTU_PPA_GPG_PRIVATE_KEY}}
       - name: dpkg-buildpackage