[SPARK-52222] Upgrade kubernetes-client to 7.3.0

### What changes were proposed in this pull request?

This PR aims to upgrade `kubernetes-client` to 7.3.0.

### Why are the changes needed?

To bring the latest bug fixes.
- https://github.com/fabric8io/kubernetes-client/releases/tag/v7.3.0

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#218 from dongjoon-hyun/SPARK-52222.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

Author: dongjoon-hyun

gradle/libs.versions.toml

@@ -15,7 +15,7 @@
 # specific language governing permissions and limitations
 # under the License.
 [versions]
-fabric8 = "7.2.0"
+fabric8 = "7.3.0"
 lombok = "1.18.38"
 operator-sdk = "4.9.0"
 okhttp = "4.12.0"