LoadLocation says:

```
// The time zone database needed by LoadLocation may not be
// present on all systems, especially non-Unix systems.
// LoadLocation looks in the directory or uncompressed zip file
// named by the ZONEINFO environment variable, if any, then looks in
// known installation locations on Unix systems,
// and finally looks in $GOROOT/lib/time/zoneinfo.zip.
```
PostgreSQL has a similar setup; you can use a database of your choosing (usually this would be one shipped with your OS), but if that doesn't exist, the project ships releases with a version which is kept up to date quite well.  In practice I wouldn't expect people to ever have a problem with these databases disagreeing on anything, but I don't see any need to take that risk.