revert: gosnowflake driver v1.6.19 -> v1.6.18

[burningalchemist]

Build error (for linux/armv7):

# github.com/apache/arrow/go/v10/internal/utils
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:76:4: undefined: TransposeInt8Int8
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:78:4: undefined: TransposeInt8Int16
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:80:4: undefined: TransposeInt8Int32
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:82:4: undefined: TransposeInt8Int64
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:84:4: undefined: TransposeInt8Uint8
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:86:4: undefined: TransposeInt8Uint16
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:88:4: undefined: TransposeInt8Uint32
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:90:4: undefined: TransposeInt8Uint64
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:95:4: undefined: TransposeInt16Int8
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:97:4: undefined: TransposeInt16Int16
Error: /go/pkg/mod/github.com/apache/arrow/go/v10@v10.0.1/internal/utils/transpose_ints_def.go:97:4: too many errors

The issue has been confirmed on the Apache Arrow side and is to be addressed in v12.

References:

• GH-34629: [Go] Fix transpose_ints to work on riscv64-freebsd apache/arrow#34647
• Fails to build Go project for Windows x86 apache/arrow#34784

We might drop armv7 in the future, but for now it seems reasonable to revert the version.