Disable chrono's default-features

[msepga]

This fixes invocations of cargo audit, where the unnecessary time dependency is pulled in.

Before:

❯ cargo audit Fetching advisory database from `https://github.com/RustSec/advisory-db.git` Loaded 464 security advisories (from /Users/msepga/.cargo/advisory-db) Updating crates.io index Scanning Cargo.lock for vulnerabilities (106 crate dependencies) Crate: time Version: 0.1.44 Title: Potential segfault in the time crate Date: 2020-11-18 ID: RUSTSEC-2020-0071 URL: https://rustsec.org/advisories/RUSTSEC-2020-0071 Solution: Upgrade to >=0.2.23 Dependency tree: time 0.1.44 └── chrono 0.4.22 ├── postgres_range 0.11.0 └── postgres-types 0.2.4 ├── tokio-postgres 0.7.7 │ └── postgres 0.19.4 │ └── postgres_range 0.11.0 └── postgres_range 0.11.0 error: 1 vulnerability found! 

After:

❯ cargo audit Fetching advisory database from `https://github.com/RustSec/advisory-db.git` Loaded 464 security advisories (from /Users/msepga/.cargo/advisory-db) Updating crates.io index Scanning Cargo.lock for vulnerabilities (104 crate dependencies)