[MINOR] Bump SparkR and PySpark version to 2.3.0.

[HyukjinKwon]

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 #16488 / #17523

How was this patch tested?

N/A

[HyukjinKwon]

I found this when testing #18335. I thought it is odd that CRAN check generated SparkR_2.2.0.tar.gz in the master. I double checked it now generates SparkR_2.3.0.tar.gz.

[HyukjinKwon]

cc @srowen and @felixcheung

[SparkQA]

Test build #78221 has finished for PR 18341 at commit 5e1bd0a.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

I think this particular field gets auto-updated during the build anyway, IIRC, so it won't matter in the way 2.3.0-SNAPSHOT matters to Maven, but to avoid confusion I think we can update it

[felixcheung]

+1 with what srowen says.
ditto with python actually https://github.com/apache/spark/blob/master/python/pyspark/version.py
i wonder if we should simply change the release/branch process to update everything

[felixcheung]

LGTM, but how about updating python too - save one less PR

[SparkQA]

Test build #78233 has finished for PR 18341 at commit 713b1b2.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

@HyukjinKwon you are also welcome to add a note to release-process.md in the spark-website repo, but that's optional (and a separate change of course)

[srowen]

Merged to master

[HyukjinKwon]

Sure, I will do. Thank you.