chore(deps): Bump protobuf from 2.24.1 to 3.7.2 in /rust/cubestore

Bumps [protobuf](https://github.com/stepancheg/rust-protobuf) from 2.24.1 to 3.7.2.
- [Changelog](https://github.com/stepancheg/rust-protobuf/blob/master/CHANGELOG-before-3.md)
- [Commits](stepancheg/rust-protobuf@v2.24.1...v3.7.2)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

rust/cubestore/Cargo.lock

@@ -8,4 +8,4 @@ description = "HyperLogLog++ implementation ported from ZetaSketch"
 
 [dependencies]
 itertools = "0.10.0"
-protobuf = "2.20.0"
+protobuf = "3.7.2"