Bump ubuntu from 74e3aaf to 9b8dec3 in /images/toolbox (#19)

Bumps ubuntu from `74e3aaf` to `9b8dec3`.

---
updated-dependencies:
- dependency-name: ubuntu
  dependency-type: direct:production
...

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

images/toolbox/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM ubuntu:22.04@sha256:74e3aaf45db3327200bcba464bc6f6863118cf3b52cf48a1d3e5038a003ec42e
+FROM ubuntu:22.04@sha256:9b8dec3bf938bc80fbe758d856e96fdfab5f56c39d44b0cff351e847bb1b01ea
 
 LABEL maintainer="Antrea <projectantrea-dev@googlegroups.com>"
 LABEL description="A Docker image with useful tools (for networking) based on Ubuntu"