Return Unique items in a Go slice
This is not idiomatic writing style in Go, because the value variable is misleading:


if _, value := keys[entry]; !value {



The first returned value is the value in the map, the second value indicates success or failure of the lookup.
So rename it to ok or found.

If the slice is very large,
then list = append(list, entry) may lead to repeated allocations.
In that case, you can optimize by preallocating list to the maximum possible capacity (len(strSlice)), and assign elements by index rather than using append.
But if you have no reason for this optimization then don't do it,
that would be premature optimization,
the current solution is fine.