chore(deps): force 0.7 version for zerocopy

The aquatic_udp_protocol crate uses version 0.7:

https://github.com/greatest-ape/aquatic/blob/master/crates/udp_protocol/Cargo.toml#L19

We were having problems with trait `read_from`. Example:

```rust
let data = PeerId::read_from(&bytes).expect("it should have the correct amount of bytes");
```

There have been changes in version 0.8:

google/zerocopy#1680

Author: josecelano

Cargo.lock

@@ -82,7 +82,7 @@ tracing = "0"
 tracing-subscriber = { version = "0", features = ["json"] }
 url = { version = "2", features = ["serde"] }
 uuid = { version = "1", features = ["v4"] }
-zerocopy = "0"
+zerocopy = "0.7"
 
 [package.metadata.cargo-machete]
 ignored = ["crossbeam-skiplist", "dashmap", "figment", "parking_lot", "serde_bytes"]

Cargo.toml

@@ -23,4 +23,4 @@ serde = { version = "1", features = ["derive"] }
 tdyne-peer-id = "1"
 tdyne-peer-id-registry = "0"
 thiserror = "1"
-zerocopy = "0"
+zerocopy = "0.7"

packages/primitives/Cargo.toml

@@ -26,7 +26,7 @@ tokio = { version = "1", features = ["macros", "net", "rt-multi-thread", "signal
 torrust-tracker-clock = { version = "3.0.0-develop", path = "../clock" }
 torrust-tracker-configuration = { version = "3.0.0-develop", path = "../configuration" }
 torrust-tracker-primitives = { version = "3.0.0-develop", path = "../primitives" }
-zerocopy = "0"
+zerocopy = "0.7"
 
 [dev-dependencies]
 async-std = { version = "1", features = ["attributes", "tokio1"] }