fix(cache-cli): allow custom S3 endpoint to be used

[lucaspin]

https://github.com/renderedtext/tasks/issues/6905

Issue

Currently, we only use a custom S3 (minio) during our tests, so we are hardcoding the minio credentials. That blocks from using a custom S3 server.

Solution

We make the custom S3 path configurable as well, and allow the key/secret pair to be configured through environment variables. One can either:

• Use SEMAPHORE_CACHE_S3_KEY and SEMAPHORE_CACHE_S3_SECRET (to avoid conflicting with the default AWS_* ones)
• If the SEMAPHORE_CACHE_* ones are not set, we default to using the default AWS ones.

Other changes

• Update Go to 1.22
• Update the jobs that used xcode14 to use xcode15 since xcode14 was disabled