Bump serde from 1.0.68 to 1.0.70

Bumps [serde](https://github.com/serde-rs/serde) from 1.0.68 to 1.0.70.
- [Release notes](https://github.com/serde-rs/serde/releases)
- [Commits](serde-rs/serde@v1.0.68...v1.0.70)

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

Author: dependabot-support

Cargo.lock

@@ -27,7 +27,7 @@ clap = "2.31.2"
 callgraph = { path = "lib/callgraph", version = "0.1.0" }
 panic_analysis = { path = "lib/panic_analysis", version = "0.1.0" }
 toml = "0.4.6"
-serde = "1.0.64"
+serde = "1.0.70"
 serde_derive = "1.0.64"
 error-chain = "0.11.0"
 serde_json = "1.0.22"