fix mod

[IANTHEREAL]

What problem does this PR solve?

import tidb/types/parser_driver for ast Expr

What is changed and how it works?

remove vendor and use go modules

Check List

Tests

• Unit test
• Integration test - https://internal.pingcap.net/jira/browse/TOOL-564
• Manual test (add detailed scripts or steps below)
  make importer and run ./bin/importer -L info -h 10.8.143.120 -P 3308 -u root -D shard_db_01 -t 'create table shard_table_01(a int unique comment '\''[[range=1,1000]]'\'', b double, c varchar(10));' -c 1 -b 1000 -n 1000

[csuzhangxc]

LGTM

[july2993]

LGTM