Fix connection errors causing failed jobs on CircleCI

[guarani]

This aims to fix errors we're seeing similar to Error: Failed to download resource "nghttp2" and ssh: connect to host github.com port 22: Operation timed out.

Running brew update was the suggested fix here and here for similar-sounding issues.

As @dcalhoun noted, #2860 updated curl but also added HOMEBREW_NO_AUTO_UPDATE=1 which prevents brew from updating when curl is installed. To try to determine if this change will cause a performance issue, the job was ran twice and both times it finished in a "normal" duration (20 to 30 minutes).

To test

Check if all CI tests pass (especially Test iOS on Device - Canaries → Upload .app to sauce labs).

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes more info and have added them to RELEASE-NOTES.txt if necessary.

[dcalhoun]

LGTM. We'll see if any degradations come after this change, but I think it is worth a try for now.

[guarani]

LGTM. We'll see if any degradations come after this change, but I think it is worth a try for now.

Thanks @dcalhoun! I'll try to keep an eye out too.