postgres panic on non-UTF-8 error message from server

[YgorSouza]

Bug Description

Tried to connect to a Postgres server with the wrong password. sqlx panicked on this method:

sqlx/sqlx-postgres/src/message/response.rs

Lines 102 to 105 in 0db12a9

	fn get_cached_str(&self, cache: (u16, u16)) -> &str {
	// unwrap: this cannot fail at this stage
	from_utf8(&self.storage[cache.0 as usize..cache.1 as usize]).unwrap()
	}

The server is installed on a Windows Server 2016 machine, and SHOW lc_messages; returns French_France.1252.

I put a dbg! just before the point where it panics, and I got this:

 Notice {
    storage: b"SFATAL\0VFATAL\0C28P01\0Mauthentification par mot de passe \xe9chou\xe9e pour l'utilisateur  \xab postgres \xbb\0Fd:\\pginstaller.auto\\postgres.windows-x64\\src\\backend\\libpq\\auth.c\0L336\0Rauth_failed\0\0",
    severity: Fatal,
    message: (
        22,
        96,
    ),
    code: (
        15,
        20,
    ),
}

It panics because of the é character, which is encoded as 0xe9 in windows-1252.

This was partially addressed by #1968, but it seems that not all fields are checked properly.

Minimal Reproduction

Just try to connect to a server as describe above, with an incorrect password.

Info

• SQLx version: 0.7.4
• SQLx features enabled: runtime-tokio-native-tls, postgres, chrono
• Database server and version: Postgres 11.0.4 on Windows Server 2016
• Operating system: Windows 11
• rustc --version: 1.79