Remove dependency on go-sql-driver/mysql

The driver was only used by parser/reserved_words_test.go, a build-tag
gated test that requires a live MySQL server. Removing the test file
drops the dependency entirely.

Author: claude

go.mod

@@ -3,7 +3,6 @@ module github.com/sqlc-dev/marino
 go 1.25
 
 require (
-	github.com/go-sql-driver/mysql v1.7.1
 	github.com/pingcap/errors v0.11.5-0.20250523034308-74f78ae071ee
 	github.com/pingcap/failpoint v0.0.0-20240528011301-b51a646c7c86
 	go.uber.org/goleak v1.3.0

go.sum

@@ -1,8 +1,6 @@
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/go-sql-driver/mysql v1.7.1 h1:lUIinVbN1DY0xBg0eMOzmmtGoHwWBbvnWubQUrtU8EI=
-github.com/go-sql-driver/mysql v1.7.1/go.mod h1:OXbVy3sEdcQ2Doequ6Z5BW6fXNQTmx+9S1MCJN5yJMI=
 github.com/pingcap/errors v0.11.5-0.20250523034308-74f78ae071ee h1:/IDPbpzkzA97t1/Z1+C3KlxbevjMeaI6BQYxvivu4u8=
 github.com/pingcap/errors v0.11.5-0.20250523034308-74f78ae071ee/go.mod h1:X2r9ueLEUZgtx2cIogM0v4Zj5uvvzhuuiu7Pn8HzMPg=
 github.com/pingcap/failpoint v0.0.0-20240528011301-b51a646c7c86 h1:tdMsjOqUR7YXHoBitzdebTvOjs/swniBTOLy5XiMtuE=