[SPARK-3397] Bump pom.xml version number of master branch to 1.2.0-SNAPSHOT

Author: GuoQiang Li <witgo@qq.com>

Closes #2268 from witgo/SPARK-3397 and squashes the following commits:

eaf913f [GuoQiang Li] Bump pom.xml version number of master branch to 1.2.0-SNAPSHOT