Format code and fix go vet

[peczenyj]

here I am using go 1.21.1 and

1. I run go fix ./...
2. Then I run make fmt
3. And finally I run go vet ./... and fix the following issues:

# github.com/redis/go-redis/v9/doctests_test
doctests/lpush_lrange_test.go:11:1: ExampleLPushLRange refers to unknown identifier: LPushLRange
doctests/set_get_test.go:11:1: ExampleSetGet refers to unknown identifier: SetGet

based on the following rules

https://pkg.go.dev/testing#hdr-Examples

enjoy