build(deps): update smallvec requirement from 0.6.10 to 1.5.1

Updates the requirements on [smallvec](https://github.com/servo/rust-smallvec) to permit the latest version.
- [Release notes](https://github.com/servo/rust-smallvec/releases)
- [Commits](https://github.com/servo/rust-smallvec/commits/v1.5.1)

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

transaction-pool/Cargo.toml

@@ -9,7 +9,7 @@ edition = "2018"
 
 [dependencies]
 log = "0.4.8"
-smallvec = "0.6.10"
+smallvec = "1.5.1"
 trace-time = { path = "../trace-time", version = "0.1" }
 
 [dev-dependencies]