build(deps): update impl-trait-for-tuples requirement (#490)

Updates the requirements on [impl-trait-for-tuples](https://github.com/bkchr/impl-trait-for-tuples) to permit the latest version.
- [Release notes](https://github.com/bkchr/impl-trait-for-tuples/releases)
- [Commits](https://github.com/bkchr/impl-trait-for-tuples/commits/v0.2)

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

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

parity-util-mem/Cargo.toml

@@ -23,7 +23,7 @@ hashbrown = { version = "0.9", optional = true }
 mimalloc = { version = "0.1.18", optional = true }
 libmimalloc-sys = { version = "0.1.14", optional = true }
 parity-util-mem-derive = { path = "derive", version = "0.1" }
-impl-trait-for-tuples = "0.1.3"
+impl-trait-for-tuples = "0.2.0"
 
 smallvec = { version = "1.0.0", optional = true }
 ethereum-types = { version = "0.10.0", optional = true, path = "../ethereum-types" }