Update sketches-ddsketch requirement from 0.2 to 0.3 (#490)

Updates the requirements on [sketches-ddsketch](https://github.com/mheffner/rust-sketches-ddsketch) to permit the latest version.
- [Release notes](https://github.com/mheffner/rust-sketches-ddsketch/releases)
- [Commits](mheffner/rust-sketches-ddsketch@v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: sketches-ddsketch
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

metrics-util/Cargo.toml

@@ -53,7 +53,7 @@ crossbeam-utils = { version = "0.8", default-features = false, optional = true }
 aho-corasick = { version = "1", default-features = false, optional = true, features = ["std"] }
 indexmap = { version = "2.1", default-features = false, features = ["std"], optional = true }
 quanta = { version = "0.12", default-features = false, optional = true }
-sketches-ddsketch = { version = "0.2", default-features = false, optional = true }
+sketches-ddsketch = { version = "0.3", default-features = false, optional = true }
 radix_trie = { version = "0.2", default-features = false, optional = true }
 ordered-float = { version = "4.2", default-features = false, optional = true }
 ahash = { version = "0.8.8", default-features = false, optional = true }
@@ -66,7 +66,7 @@ rand = { version = "0.8", features = ["small_rng"] }
 rand_distr = "0.4"
 getopts = "0.2"
 hdrhistogram = { version = "7.2", default-features = false }
-sketches-ddsketch = "0.2"
+sketches-ddsketch = "0.3"
 ndarray = "0.15"
 ndarray-stats = "0.5"
 noisy_float = "0.2"