Version 1.7

Changes:

• Drop support of Go 1.12 (#1211)
• Refactoring (*textRows).readRow in a more clear way (#1230)
• util: Reduce boundary check in escape functions. (#1316)
• enhancement for mysqlConn handleAuthResult (#1250)

New Features:

• support Is comparison on MySQLError (#1210)
• return unsigned in database type name when necessary (#1238)
• Add API to express like a --ssl-mode=PREFERRED MySQL client (#1370)
• Add SQLState to MySQLError (#1321)

Bugfixes:

• Fix parsing 0 year. (#1257)