[MAINT] Unpin coverage workflow

[ndgrigorian]

The coverage workflow was pinned due to a break in the 2026.0 compiler, which should be fixed in 2026.1

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?
• If this PR is a work in progress, are you opening the PR as a draft?

[coveralls]

coverage: 73.229% (-1.4%) from 74.579% — unpin-coverage-workflow-compiler-version into master

[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/2352/index.html