multimod: diff command errors run Windows

[scorpionknifes]

Running multimod diff fails on clean worktree on Windows

> multimod diff -m tools -p 1.2.3 
error running diff: VerifyWorkingTreeClean failed: working tree not clean

Related issues with go-git: go-git/go-git#691

opentelemetry-go-build-tools/multimod/internal/common/git.go

Lines 147 to 150 in ff1ce4b

	status, err := worktree.Status()
	if err != nil {
	return fmt.Errorf("could not get worktree status: %w", err)
	}

Related tests failing: https://github.com/open-telemetry/opentelemetry-go-build-tools/actions/runs/7216411029/job/19662557783?pr=466
Originally posted: #466 (comment)