Update zerocopy requirement from 0.6.0 to 0.7.9

Updates the requirements on [zerocopy](https://github.com/google/zerocopy) to permit the latest version.
- [Commits](google/zerocopy@v0.6.0...v0.7.9)

---
updated-dependencies:
- dependency-name: zerocopy
  dependency-type: direct:production
...

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

Cargo.toml

@@ -61,7 +61,7 @@ rand_distr = "0.3"
 quickcheck = "0.9"
 log = "0.4.14"
 env_logger = "0.9.0"
-zerocopy = "0.6.0"
+zerocopy = "0.7.9"
 byteorder = "1.4.3"
 
 [[test]]