maint(deps): bump github.com/DataDog/zstd from 1.5.5 to 1.5.6

Bumps [github.com/DataDog/zstd](https://github.com/DataDog/zstd) from 1.5.5 to 1.5.6.
- [Release notes](https://github.com/DataDog/zstd/releases)
- [Commits](DataDog/zstd@v1.5.5...v1.5.6)

---
updated-dependencies:
- dependency-name: github.com/DataDog/zstd
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

go.mod

@@ -3,7 +3,7 @@ module github.com/honeycombio/libhoney-go
 go 1.19
 
 require (
-	github.com/DataDog/zstd v1.5.5
+	github.com/DataDog/zstd v1.5.6
 	github.com/facebookgo/muster v0.0.0-20150708232844-fd3d7953fd52
 	github.com/klauspost/compress v1.17.9
 	github.com/stretchr/testify v1.9.0

go.sum

@@ -1,5 +1,5 @@
-github.com/DataDog/zstd v1.5.5 h1:oWf5W7GtOLgp6bciQYDmhHHjdhYkALu6S/5Ni9ZgSvQ=
-github.com/DataDog/zstd v1.5.5/go.mod h1:g4AWEaM3yOg3HYfnJ3YIawPnVdXJh9QME85blwSAmyw=
+github.com/DataDog/zstd v1.5.6 h1:LbEglqepa/ipmmQJUDnSsfvA8e8IStVcGaFWDuxvGOY=
+github.com/DataDog/zstd v1.5.6/go.mod h1:g4AWEaM3yOg3HYfnJ3YIawPnVdXJh9QME85blwSAmyw=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/facebookgo/clock v0.0.0-20150410010913-600d898af40a h1:yDWHCSQ40h88yih2JAcL6Ls/kVkSE8GFACTGVnMPruw=