compose/loader: fix TestIsAbs not testing all combinations
compose/loader: fix TestIsAbs not testing all combinations

This test was intending to run all tests, but didn't, which was
caught by golangci-lint;

    cli/compose/loader/windows_path_test.go:46:17: SA4010: this result of append is never used, except maybe in other appends (staticcheck)
    	tests := append(isabstests, winisabstests...)
    	               ^

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

docker/cli,cpuguy83/cli,cpuguy83/cli,docker/cli,thaJeztah/cli,thaJeztah/cli