Fixed short-path tests.

[cmaglie]

The failing CI is due to the GitHub runners not supporting short paths.

On my local Windows machine:

=== RUN   TestEquivalentPaths
     paths_test.go:343: SHORTENED PATH: testdata\fileset\ANOTHE~1
--- PASS: TestEquivalentPaths (0.00s)
=== RUN   TestCanonicalize
     paths_test.go:361: SHORTENED PATH: testdata\fileset\ANOTHE~1
--- PASS: TestCanonicalize (0.00s)

On GitHub CI:

=== RUN   TestEquivalentPaths
    paths_test.go:343: SHORTENED PATH: testdata\fileset\anotherFile
--- PASS: TestEquivalentPaths (0.00s)
=== RUN   TestCanonicalize
    paths_test.go:361: SHORTENED PATH: testdata\fileset\anotherFile
--- PASS: TestCanonicalize (0.00s)