build: bump serde_json from 1.0.75 to 1.0.78 in /fuzz

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.75 to 1.0.78.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](https://github.com/serde-rs/json/compare/v1.0.75...v1.0.78)

---
updated-dependencies:
- dependency-name: serde_json
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

fuzz/Cargo.lock

@@ -567,9 +567,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.75"
+version = "1.0.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c059c05b48c5c0067d4b4b2b4f0732dd65feb52daf7e0ea09cd87e7dadc1af79"
+checksum = "d23c1ba4cf0efd44be32017709280b32d1cea5c3f1275c3b6d9e8bc54f758085"
 dependencies = [
  "itoa",
  "ryu",