[MINOR] Bump SparkR and PySpark version to 2.3.0.

## What changes were proposed in this pull request?

#17753 bumps master branch version to 2.3.0-SNAPSHOT, but it seems SparkR and PySpark version were omitted.

ditto of https://github.com/apache/spark/pull/16488 / https://github.com/apache/spark/pull/17523

## How was this patch tested?

N/A

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #18341 from HyukjinKwon/r-version.

R/pkg/DESCRIPTION

 Package: SparkR
 Type: Package
-Version: 2.2.0
+Version: 2.3.0
 Title: R Frontend for Apache Spark
 Description: The SparkR package provides an R Frontend for Apache Spark.
 Authors@R: c(person("Shivaram", "Venkataraman", role = c("aut", "cre"),

python/pyspark/version.py

@@ -16,4 +16,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = "2.2.0.dev0"
+__version__ = "2.3.0.dev0"