Enable bzlmod for release workflow

[jklukas]

When I pushed tag 'v0.1.6' the release workflow failed (see https://github.com/bazeltools/bazel_jar_jar/actions/runs/13838887980). The test step threw the following:

ERROR: Skipping '//...': error loading package under directory '': error loading package '~/.cache/bazel-repo/bazel/_bazel_runner/3399e9710025216540c9400ff7b0a534/external/bazel_tools/src/conditions': Label '//tools/windows:windows_config.bzl' is invalid because 'tools/windows' is not a package; perhaps you meant to put the colon here: '//:tools/windows/windows_config.bzl'?
ERROR: error loading package under directory '': error loading package '~/.cache/bazel-repo/bazel/_bazel_runner/3399e9710025216540c9400ff7b0a534/external/bazel_tools/src/conditions': Label '//tools/windows:windows_config.bzl' is invalid because 'tools/windows' is not a package; perhaps you meant to put the colon here: '//:tools/windows/windows_config.bzl'?

The current version of the Test action enables bzlmod, so we update the release flow to do the same.

I went ahead and retagged v0.1.6 with these changes and the workflow was successful.