Paths are not normalized

[gadomski]

The output paths can contain unnecessary . characters if the STAC object link hrefs use them. E.g.:

$ stac-validator --recursive --lint ../stactools/tests/data-files/catalogs/test-case-1/catalog.json | jq '.[].path'
"../stactools/tests/data-files/catalogs/test-case-1/catalog.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/catalog.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/./area-1-1/collection.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/./area-1-1/./area-1-1-imagery/area-1-1-imagery.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/./area-1-1/./area-1-1-labels/area-1-1-labels.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/./area-1-2/collection.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/./area-1-2/./area-1-2-imagery/area-1-2-imagery.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-1/./area-1-2/./area-1-2-labels/area-1-2-labels.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/catalog.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/./area-2-1/collection.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/./area-2-1/./area-2-1-imagery/area-2-1-imagery.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/./area-2-1/./area-2-1-labels/area-2-1-labels.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/./area-2-2/collection.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/./area-2-2/./area-2-2-imagery/area-2-2-imagery.json"
"../stactools/tests/data-files/catalogs/test-case-1/./country-2/./area-2-2/./area-2-2-labels/area-2-2-labels.json"

While not technically incorrect, it may be nicer to normalize the paths before returning.