use "path/filepath" to build file path

[seiyab]

I found path.Dir() which looks misuse.

package "path" suggests:

The path package should only be used for paths separated by forward slashes, such as the paths in URLs. This package does not deal with Windows paths with drive letters or backslashes; to manipulate operating system paths, use the path/filepath package.

NOTE: I found this just scanning project statically. I haven't reproduced "real" problem. Even I don't have Windows environment.

This line looks to be covered by existing test.

grype/internal/format/writer_test.go

Lines 173 to 178 in 548da9e

	case *scanResultStreamWriter:
	assert.Equal(t, string(w.format), e.format)
	assert.NotNil(t, w.out)
	if e.file != "" {
	assert.FileExists(t, tmp+e.file)
	}

[kzantow]

Thanks @seiyab! You're right, this function could be OS dependent and looks to be already covered by tests, at least on linux. 👍