chore(deps): bump github.com/docker/distribution

Bumps [github.com/docker/distribution](https://github.com/docker/distribution) from 2.8.0+incompatible to 2.8.1+incompatible.
- [Release notes](https://github.com/docker/distribution/releases)
- [Commits](distribution/distribution@v2.8.0...v2.8.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -5,7 +5,7 @@ go 1.12
 require (
 	github.com/containrrr/shoutrrr v0.6.1
 	github.com/docker/cli v20.10.17+incompatible
-	github.com/docker/distribution v2.8.0+incompatible
+	github.com/docker/distribution v2.8.1+incompatible
 	github.com/docker/docker v20.10.17+incompatible
 	github.com/docker/go-connections v0.4.0
 	github.com/johntdyer/slackrus v0.0.0-20180518184837-f7aae3243a07

go.sum

@@ -41,8 +41,8 @@ github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZm
 github.com/dgryski/go-sip13 v0.0.0-20181026042036-e10d5fee7954/go.mod h1:vAd38F8PWV+bWy6jNmig1y/TA+kYO4g3RSRF0IAv0no=
 github.com/docker/cli v20.10.17+incompatible h1:eO2KS7ZFeov5UJeaDmIs1NFEDRf32PaqRpvoEkKBy5M=
 github.com/docker/cli v20.10.17+incompatible/go.mod h1:JLrzqnKDaYBop7H2jaqPtU4hHvMKP+vjCwu2uszcLI8=
-github.com/docker/distribution v2.8.0+incompatible h1:l9EaZDICImO1ngI+uTifW+ZYvvz7fKISBAKpg+MbWbY=
-github.com/docker/distribution v2.8.0+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
+github.com/docker/distribution v2.8.1+incompatible h1:Q50tZOPR6T/hjNsyc9g8/syEs6bk8XXApsHjKukMl68=
+github.com/docker/distribution v2.8.1+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
 github.com/docker/docker v20.10.17+incompatible h1:JYCuMrWaVNophQTOrMMoSwudOVEfcegoZZrleKc1xwE=
 github.com/docker/docker v20.10.17+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
 github.com/docker/docker-credential-helpers v0.6.1 h1:Dq4iIfcM7cNtddhLVWe9h4QDjsi4OER3Z8voPu/I52g=