build: upgrade github.com/vmihailenco/msgpack to v5

[jaimem88]

msgpack is now using modules as of v5+, this PR upgrades the library to the latest version v5.3.5. From the changelog, there are a few breaking changes, however, none of them affect the usage of the library here.

[jaimem88]

go test ./...
ok  	github.com/eko/gocache/lib/v4/cache	1.544s
ok  	github.com/eko/gocache/lib/v4/codec	0.828s
ok  	github.com/eko/gocache/lib/v4/marshaler	0.587s
ok  	github.com/eko/gocache/lib/v4/metrics	1.512s
ok  	github.com/eko/gocache/lib/v4/store	1.659s

[jaimem88]

@eko 👋 would you consider merging this PR?

[eko]

Thank you for this upgrade of msgpack @jaimem88