fix: columns map to prevent concurrent write and read

[Maxibond]

Sometimes running a code generation, I receive an error caused by concurrent read and map writes to the columns map.
Sync.Map will prevent it.

sqlboiler -c ./sqlboiler.toml psql

fatal error: concurrent map read and map write



goroutine 22 [running]:

github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-psql/driver.(*PostgresDriver).Columns(0xc000030540, {0x6ca5dc, 0x6}, {0xc0000a6140, 0xb}, {0x0, 0x0, 0x0}, {0xc000068df0, 0x1, ...})

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/sqlboiler-psql/driver/psql.go:610 +0x8a9

github.com/volatiletech/sqlboiler/v4/drivers.table({0x75de78, 0xc000030540}, {0x6ca5dc, 0x6}, {0xc0000a6140, 0xb}, {0x0, 0x0, _}, {0xc000068df0, ...})

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/interface.go:192 +0x128

github.com/volatiletech/sqlboiler/v4/drivers.tables.func1(0x4, {0xc0000a6140?, 0x0?})

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/interface.go:156 +0x1cf

created by github.com/volatiletech/sqlboiler/v4/drivers.tables

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/interface.go:153 +0x585



goroutine 1 [chan receive]:

github.com/volatiletech/sqlboiler/v4/drivers.concurrencyLimiter.get(...)

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/interface.go:388

github.com/volatiletech/sqlboiler/v4/drivers.tables({0x75de78, 0xc000030540}, {0x6ca5dc, 0x6}, {0x0?, 0x0, 0x0}, {0xc000068df0, 0x1, 0x1}, ...)

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/interface.go:152 +0x325

github.com/volatiletech/sqlboiler/v4/drivers.TablesConcurrently({0x75de78, 0xc000030540}, {0x6ca5dc, 0x6}, {0x0, 0x0, 0x0}, {0xc000068df0, 0x1, 0x1}, ...)

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/interface.go:119 +0x8e

github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-psql/driver.(*PostgresDriver).Assemble(0xc000030540, 0xcc?)

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/sqlboiler-psql/driver/psql.go:134 +0x83a

github.com/volatiletech/sqlboiler/v4/drivers.DriverMain({0x75d4f0, 0xc000030540})

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/driver_main.go:37 +0x496

main.main()

	/go/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.12.0/drivers/sqlboiler-psql/main.go:9 +0x34