chore: use go 1.20 idiomatic string<->byte conversion

[justinhwang]

As of Go 1.20, this is the idiomatic way to convert from Bytes to String and vice-versa.

This updates go.mod to 1.20, builds have already been running on 1.23.x and 1.24.x since #3274.

Benchmarks

Benchmarks show no change:

goos: darwin
goarch: arm64
pkg: github.com/redis/go-redis/v9/internal/util
cpu: Apple M3 Max
BenchmarkStringToBytes/copy-16         	112308339	        10.61 ns/op	      24 B/op	       1 allocs/op
BenchmarkStringToBytes/unsafe-16       	1000000000	         0.9967 ns/op	       0 B/op	       0 allocs/op
BenchmarkBytesToString/copy-16         	134565944	         8.884 ns/op	      24 B/op	       1 allocs/op
BenchmarkBytesToString/unsafe-16       	1000000000	         0.4511 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/redis/go-redis/v9/internal/util	6.001s

goos: darwin
goarch: arm64
pkg: github.com/redis/go-redis/v9/internal/util
cpu: Apple M3 Max
BenchmarkStringToBytes/copy-16         	112317182	        10.56 ns/op	      24 B/op	       1 allocs/op
BenchmarkStringToBytes/unsafe-16       	1000000000	         0.6711 ns/op	       0 B/op	       0 allocs/op
BenchmarkBytesToString/copy-16         	135204112	         8.874 ns/op	      24 B/op	       1 allocs/op
BenchmarkBytesToString/unsafe-16       	1000000000	         0.5666 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/redis/go-redis/v9/internal/util	5.753s

name                     old time/op    new time/op    delta
StringToBytes/copy-16      10.6ns ± 0%    10.6ns ± 0%   ~     (p=1.000 n=1+1)
StringToBytes/unsafe-16    1.00ns ± 0%    0.67ns ± 0%   ~     (p=1.000 n=1+1)
BytesToString/copy-16      8.88ns ± 0%    8.87ns ± 0%   ~     (p=1.000 n=1+1)
BytesToString/unsafe-16    0.45ns ± 0%    0.57ns ± 0%   ~     (p=1.000 n=1+1)

name                     old alloc/op   new alloc/op   delta
StringToBytes/copy-16       24.0B ± 0%     24.0B ± 0%   ~     (all equal)
StringToBytes/unsafe-16     0.00B          0.00B        ~     (all equal)
BytesToString/copy-16       24.0B ± 0%     24.0B ± 0%   ~     (all equal)
BytesToString/unsafe-16     0.00B          0.00B        ~     (all equal)

name                     old allocs/op  new allocs/op  delta
StringToBytes/copy-16        1.00 ± 0%      1.00 ± 0%   ~     (all equal)
StringToBytes/unsafe-16      0.00           0.00        ~     (all equal)
BytesToString/copy-16        1.00 ± 0%      1.00 ± 0%   ~     (all equal)
BytesToString/unsafe-16      0.00           0.00        ~     (all equal)

[justinhwang]

@ndyakov do you think you could help take a look? thanks!

[ndyakov]

@justinhwang Thank you for your contribution. I do like the idea and would like to upgrade to a newer go version, but we discussed to put this one back a bit since it would be a breaking change and we would have to release a new major version. I will tag this PR and review / merge it once we get there (hopefully sooner and previously expected).

[justinhwang]

@ndyakov It isn't a breaking change no? Semantically it does the same thing under the hood, just uses Go 1.20's safer way of doing it. Unless you're referring to the Go version bump as a breaking change

[ndyakov]

@justinhwang yes, I am referring to bumping go to a new version as a "breaking change" since users will have to upgrade to a new version and this may actually not work well for all of them.

[justinhwang]

ack yeah that makes sense. Please feel free to merge whenever you're ready for v10!