Ci is currently failing on brew update with the error:
```
Error: Cannot install bazelisk because conflicting formulae are installed.
bazel: because Bazelisk replaces the bazel binary
Please `brew unlink bazel` before continuing.
Unlinking removes a formula's symlinks from /usr/local. You can
link the formula again after the install finishes. You can --force this
install, but the build may fail or cause obscure side effects in the
resulting software.
```
Avoiding:
```
$ brew update
$ brew upgrade
```
solves the issue by preventing the risk of conflicting formulae
Style and documentation tests take just a few minutes
to run. Since in Github actions one can't restart a single
job but needs to restart an entire workflow, here we group
tests with similar duration together.
