brew-rs: enable compression in reqwest

[samford]

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This adds gzip and deflate features from the reqwest crate and enables compression in the build_client function. There are also brotli and zstd features but I've used the compression methods that we're already using in curl. gzip is the best we can get from the servers that we're currently using, so there isn't any benefit to the other compression methods for now.

For what it's worth, reqwest takes care of automatically adding the Accept-Encoding header to requests and decompressing responses that have a Content-Encoding header. In the process, it removes Content-Encoding and Content-Length headers from the response, so it's a little tricky to tell if it's working but I manually verified the behavior.

[Copilot]

Pull request overview

This PR updates the brew-rs HTTP client configuration to negotiate compressed HTTP responses using reqwest, aiming to reduce transfer sizes (particularly for API/JSON payloads).

Changes:

• Enable reqwest’s gzip and deflate features in brew-rs’s Cargo.toml.
• Turn on gzip/deflate support in the shared reqwest::blocking::Client built by build_client().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
Library/Homebrew/rust/brew-rs/src/commands/fetch.rs	Enables gzip/deflate on the shared reqwest client used by fetch flows.
Library/Homebrew/rust/brew-rs/Cargo.toml	Adds reqwest compression features (gzip, deflate) to the dependency configuration.

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[Copilot]

Enabling reqwest gzip/deflate at the shared ClientBuilder level affects bottle downloads too. If any bottle host returns a Content-Encoding (e.g., gzip) response, reqwest will transparently decompress and the on-disk bytes will no longer match the expected bottle SHA-256, causing fetch failures or writing unexpected content. Consider limiting compression to API/JSON requests only (e.g., use a separate client for metadata, or force Accept-Encoding: identity on bottle requests).

Suggested change

	.gzip(true)
	.deflate(true)

[samford]

I thought about this but the server for bottles ignores an Accept-Encoding header in requests and doesn't use a Content-Encoding header in the response.