* fix: use latest version of jdbc connector
* fix: remove locale and timezone to avoid confusing user
* fix: update readme.md
* fix: refine demo.c
* fix: specify utf-8 in jdbc example pom.xml
* fix(driver): jdbc sample for 3.0
* fix: drop table if exists
* test: valgrind case
Co-authored-by: Shengliang Guan <slguan@taosdata.com>
Co-authored-by: Shuduo Sang <sangshuduo@gmail.com>