Cargo: add socks feature to reqwest

[jbtrystram]

Add SOCKS5 support to Zincati by enabling the appropriate feature flag for the reqwest dependency. Reqwest should pull in the proxy config from the environment.

Fixes coreos/fedora-coreos-tracker#2067

[gemini-code-assist]

Code Review

This pull request adds SOCKS5 proxy support by enabling the socks feature for the reqwest dependency. The change is correct and addresses the linked issue. I have one suggestion to improve the maintainability of your Cargo.toml by making the dependency features more explicit, following a pattern already used for other dependencies in the file.

[gemini-code-assist]

To improve consistency with other dependencies in this file (like prometheus) and to make the feature set more explicit, consider disabling the default features of reqwest and specifying the required features directly. This makes it clearer which TLS backend is in use and prevents accidentally enabling new default features in future reqwest updates.

Suggested change

	reqwest = { version = "0.12", features = ["json", "socks"] }
	reqwest = { version = "0.12", default-features = false, features = ["json", "native-tls", "socks"] }