[SPARK-26897][SQL][TEST] Update Spark 2.3.x testing from HiveExternalCatalogVersionsSuite

## What changes were proposed in this pull request?
The maintenance release of `branch-2.3` (v2.3.3) vote passed, so this issue updates PROCESS_TABLES.testingVersions in HiveExternalCatalogVersionsSuite

## How was this patch tested?
Pass the Jenkins.

Closes apache#23807 from maropu/SPARK-26897.

Authored-by: Takeshi Yamamuro <[email protected]>
Signed-off-by: Takeshi Yamamuro <[email protected]>

Author: maropu

sql/hive/src/test/scala/org/apache/spark/sql/hive/HiveExternalCatalogVersionsSuite.scala

@@ -206,7 +206,7 @@ class HiveExternalCatalogVersionsSuite extends SparkSubmitTestUtils {
 
 object PROCESS_TABLES extends QueryTest with SQLTestUtils {
   // Tests the latest version of every release line.
-  val testingVersions = Seq("2.3.2", "2.4.0")
+  val testingVersions = Seq("2.3.3", "2.4.0")
 
   protected var spark: SparkSession = _