[SEDONA-138] Fix ST_GeoHash for Flink to work

[sekikn]

Did you read the Contributor Guide?

• Yes, I have read Contributor Rules and Contributor Development Guide

Is this PR related to a JIRA ticket?

• Yes, the URL of the assoicated JIRA ticket is https://issues.apache.org/jira/browse/SEDONA-138. The PR name follows the format [SEDONA-XXX] my subject.

What changes were proposed in this PR?

Currently the ST_GeoHash function for Flink fails with EOFException. This PR fixes it.

How was this patch tested?

By running mvn test -pl flink locally. In addition, I ran the following query from a Flink application:

SELECT ST_GeoHash(ST_Point(0, 1), 5)

then got the following result.

+--------------------------------+
|                         EXPR$0 |
+--------------------------------+
|                          s00j8 |
+--------------------------------+

Did this PR include necessary documentation updates?

• No, this PR does not affect any public API so no need to change the docs.

[jiayuasu]

To be merged after this PR: #647