chore: Fix race in go progress

[willmurphyscode]

Previously, setting Current on the stager was technically a race condition, since the reference was shared between go routines. go-progress added an atomic version of stager that atomically updates the current stage (wagoodman/go-progress#2). Upgrade to use that stager implementation, and pass -race to the unit test step to help prevent new race conditions from being introduced.

The next step will be to merge this into syft, see comparison: https://github.com/anchore/syft/compare/fix-go-progress-race

[github-actions]

Benchmark Test Results

Benchmark results from the latest changes vs base branch

latest: Pulling from library/ubuntu
tar: Option --mtime: Treating date 'UTC 2019-09-16' as 2019-09-16 00:00:00
goos: linux
goarch: amd64
pkg: github.com/anchore/stereoscope/pkg/file
cpu: Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz
docker: 
           │ ./.tmp/benchmark-e08f009.txt │
           │            sec/op            │
TarIndex-2                   44.18µ ± ∞ ¹
¹ need >= 6 samples for confidence interval at level 0.95

           │ ./.tmp/benchmark-e08f009.txt │
           │             B/op             │
TarIndex-2                  5.560Ki ± ∞ ¹
¹ need >= 6 samples for confidence interval at level 0.95

           │ ./.tmp/benchmark-e08f009.txt │
           │          allocs/op           │
TarIndex-2                    93.00 ± ∞ ¹
¹ need >= 6 samples for confidence interval at level 0.95

pkg: github.com/anchore/stereoscope/test/integration
                                      │ ./.tmp/benchmark-e08f009.txt │
                                      │            sec/op            │
SimpleImage_GetImage/docker-archive-2                   1.440m ± ∞ ¹
SimpleImage_GetImage/oci-archive-2                      1.437m ± ∞ ¹
SimpleImage_GetImage/oci-dir-2                          1.129m ± ∞ ¹
geomean                                                 1.327m
¹ need >= 6 samples for confidence interval at level 0.95

                                      │ ./.tmp/benchmark-e08f009.txt │
                                      │             B/op             │
SimpleImage_GetImage/docker-archive-2                  328.0Ki ± ∞ ¹
SimpleImage_GetImage/oci-archive-2                     645.7Ki ± ∞ ¹
SimpleImage_GetImage/oci-dir-2                         413.0Ki ± ∞ ¹
geomean                                                443.9Ki
¹ need >= 6 samples for confidence interval at level 0.95

                                      │ ./.tmp/benchmark-e08f009.txt │
                                      │          allocs/op           │
SimpleImage_GetImage/docker-archive-2                   2.736k ± ∞ ¹
SimpleImage_GetImage/oci-archive-2                      1.570k ± ∞ ¹
SimpleImage_GetImage/oci-dir-2                          1.354k ± ∞ ¹
geomean                                                 1.798k
¹ need >= 6 samples for confidence interval at level 0.95

docker: Error response from daemon: Get "http://localhost/v2/": dial tcp [::1]:80: connect: connection refused.
                                                   │ ./.tmp/benchmark-e08f009.txt │
                                                   │            sec/op            │
SimpleImage_FetchSquashedContents/docker-archive-2                   17.60µ ± ∞ ¹
¹ need >= 6 samples for confidence interval at level 0.95

                                                   │ ./.tmp/benchmark-e08f009.txt │
                                                   │             B/op             │
SimpleImage_FetchSquashedContents/docker-archive-2                  2.648Ki ± ∞ ¹
¹ need >= 6 samples for confidence interval at level 0.95

                                                   │ ./.tmp/benchmark-e08f009.txt │
                                                   │          allocs/op           │
SimpleImage_FetchSquashedContents/docker-archive-2                    21.00 ± ∞ ¹
¹ need >= 6 samples for confidence interval at level 0.95