fix: avoid int overflow errors with DurationUnit && DataSizeUnit

[jstrachan]

I hit this bug when trying to use goreleaser on a project using pkl-go as it failed with errors like the following.

Note I'm not sure why goreleaser finds these issues but other go targets don't; I guess its one of the golang linters maybe?

pkl/values.go:111:29: Second * 60 (constant 60000000000 of type DurationUnit) overflows int;
pkl/values.go:238:7: Terabytes (untyped int constant 1000000000000) overflows int;
pkl/values.go:240:7: Tebibytes (untyped int constant 1099511627776) overflows int;
pkl/values.go:242:7: Petabytes (untyped int constant 1000000000000000) overflows int;
pkl/values.go:244:7: Pebibytes (untyped int constant 1125899906842624) overflows int;
pkl/values.go:279:10: cannot use Terabytes (untyped int constant 1000000000000) as DataSizeUnit value in return statement (overflows);
pkl/values.go:281:10: cannot use Tebibytes (untyped int constant 1099511627776) as DataSizeUnit value in return statement (overflows);
pkl/values.go:283:10: cannot use Petabytes (untyped int constant 1000000000000000) as DataSizeUnit value in return statement (overflows);
pkl/values.go:285:10: cannot use Pebibytes (untyped int constant 1125899906842624) as DataSizeUnit value in return statement (overflows);

[holzensp]

Could goreleaser somehow force 32-bit word size?

[holzensp]

LGTM