go get -u github.com/a8m/enter now requires go 1.22

Unable to install `enter` - output says it requires go 1.22
install command:
```
go get -u github.com/a8m/enter

```
output:
```
github.com/a8m/enter imports
entgo.io/ent/entc/gen imports
ariga.io/atlas/sql/postgres imports
ariga.io/atlas/sql/internal/specutil imports
slices: package slices is not in GOROOT (/usr/local/go/src/slices)
note: imported by a module that requires go 1.22
```

Current version: go 1.20.5

Check the go.mod file to see the required Go version. Look for any version constraints or dependencies that require Go 1.22, such as the 'slices' package. Update the documentation or build configuration to clarify the minimum Go version needed. Verify by attempting to build the project with Go 1.20.5 to reproduce the error.

索引モデルが issue の本文から書いたものです。