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

Bumps [github.com/docker/distribution](https://github.com/docker/distribution) from 2.7.1+incompatible to 2.8.0+incompatible.
- [Release notes](https://github.com/docker/distribution/releases)
- [Commits](https://github.com/docker/distribution/compare/v2.7.1...v2.8.0)

---
updated-dependencies:
- dependency-name: github.com/docker/distribution
  dependency-type: direct:production
...

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

vendor/github.com/docker/distribution/.mailmap

@@ -30,3 +30,17 @@ Helen Xie <xieyulin821@harmonycloud.cn> Helen-xie <xieyulin821@harmonycloud.cn>
 Mike Brown <brownwm@us.ibm.com> Mike Brown <mikebrow@users.noreply.github.com>
 Manish Tomar <manish.tomar@docker.com> Manish Tomar <manishtomar@users.noreply.github.com>
 Sakeven Jiang <jc5930@sina.cn> sakeven <jc5930@sina.cn>
+Milos Gajdos <milosgajdos83@gmail.com> Milos Gajdos <milosgajdos@users.noreply.github.com>
+Derek McGowan <derek@mcgstyle.net> Derek McGowa <dmcgowan@users.noreply.github.com>
+Adrian Plata <adrian.plata@docker.com> Adrian Plata <@users.noreply.github.com>
+Sebastiaan van Stijn <github@gone.nl> Sebastiaan van Stijn <thaJeztah@users.noreply.github.com>
+Vishesh Jindal <vishesh92@gmail.com> Vishesh Jindal <vishesh92@users.noreply.github.com>
+Wang Yan <wangyan@vmware.com> Wang Yan <wy65701436@users.noreply.github.com>
+Chris Patterson <chrispat@github.com> Chris Patterson <chrispat@users.noreply.github.com>
+Eohyung Lee <liquidnuker@gmail.com> Eohyung Lee <leoh0@users.noreply.github.com>
+João Pereira <484633+joaodrp@users.noreply.github.com>
+Smasherr <soundcracker@gmail.com> Smasherr <Smasherr@users.noreply.github.com>
+Thomas Berger <loki@lokis-chaos.de> Thomas Berger <tbe@users.noreply.github.com>
+Samuel Karp <skarp@amazon.com> Samuel Karp <samuelkarp@users.noreply.github.com>
+Justin Cormack <justin.cormack@docker.com>
+sayboras <sayboras@yahoo.com>