docs: fix SQLx CLI installation (#2133)

## What ❔

Updates the installing instructions for SQLx CLI

## Why ❔

Problems when compiling `clap_lex`:
`error[E0599]: no method named `as_encoded_bytes` found for reference
`&OsStr` in the current scope`
`error[E0599]: no function or associated item named
`from_encoded_bytes_unchecked` found for struct `OsStr` in the current
scope`

docs/guides/setup-dev.md

@@ -221,7 +221,7 @@ SQLx is a Rust library we use to interact with Postgres, and its CLI is used to
 features of the library.
 
 ```bash
-cargo install sqlx-cli --version 0.7.3
+cargo install --locked sqlx-cli --version 0.7.3
 ```
 
 ## Solidity compiler `solc`