build(deps): bump github.com/docker/docker

Bumps [github.com/docker/docker](https://github.com/docker/docker) from 20.10.18+incompatible to 20.10.21+incompatible.
- [Release notes](https://github.com/docker/docker/releases)
- [Changelog](https://github.com/moby/moby/blob/master/CHANGELOG.md)
- [Commits](moby/moby@v20.10.18...v20.10.21)

---
updated-dependencies:
- dependency-name: github.com/docker/docker
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/buildpacks/imgutil v0.0.0-20220913203928-6accc39f0cf9
 	github.com/buildpacks/lifecycle v0.14.2
 	github.com/docker/cli v20.10.21+incompatible
-	github.com/docker/docker v20.10.18+incompatible
+	github.com/docker/docker v20.10.21+incompatible
 	github.com/docker/go-connections v0.4.0
 	github.com/dustin/go-humanize v1.0.0
 	github.com/gdamore/tcell/v2 v2.5.3

go.sum

@@ -467,8 +467,9 @@ github.com/docker/distribution v2.8.1+incompatible h1:Q50tZOPR6T/hjNsyc9g8/syEs6
 github.com/docker/distribution v2.8.1+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
 github.com/docker/docker v1.4.2-0.20190924003213-a8608b5b67c7/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
 github.com/docker/docker v20.10.17+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
-github.com/docker/docker v20.10.18+incompatible h1:SN84VYXTBNGn92T/QwIRPlum9zfemfitN7pbsp26WSc=
 github.com/docker/docker v20.10.18+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
+github.com/docker/docker v20.10.21+incompatible h1:UTLdBmHk3bEY+w8qeO5KttOhy6OmXWsl/FEet9Uswog=
+github.com/docker/docker v20.10.21+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
 github.com/docker/docker-credential-helpers v0.6.3/go.mod h1:WRaJzqw3CTB9bk10avuGsjVBZsD05qeibJ1/TYlvc0Y=
 github.com/docker/docker-credential-helpers v0.6.4 h1:axCks+yV+2MR3/kZhAmy07yC56WZ2Pwu/fKWtKuZB0o=
 github.com/docker/docker-credential-helpers v0.6.4/go.mod h1:ofX3UI0Gz1TteYBjtgs07O36Pyasyp66D2uKT7H8W1c=