Bump bazelisk version to v1.28.1

This is the most recent release at the moment. Important changes from
v1.11.0 include support for bzlmod project roots. The old version
doesn't find a `.bazelversion` file in pure bzlmod projects because it
doesn't recognize the project root without a WORKSPACE file. bzlmod
projects require only a MODULE.bazel file.

Issue: 492561165
Change-Id: Ia95c88c04e3551b2fae113d3b40371a388b58e30