rebase: bump github.com/ceph/go-ceph from 0.20.0 to 0.21.0

Bumps [github.com/ceph/go-ceph](https://github.com/ceph/go-ceph) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/ceph/go-ceph/releases)
- [Changelog](https://github.com/ceph/go-ceph/blob/master/docs/release-process.md)
- [Commits](https://github.com/ceph/go-ceph/compare/v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: github.com/ceph/go-ceph
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

go.sum

@@ -195,8 +195,8 @@ github.com/cenkalti/backoff/v4 v4.1.3 h1:cFAlzYUlVYDysBEH2T5hyJZMh3+5+WCBvSnK6Q8
 github.com/cenkalti/backoff/v4 v4.1.3/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/centrify/cloud-golang-sdk v0.0.0-20190214225812-119110094d0f/go.mod h1:C0rtzmGXgN78pYR0tGJFhtHgkbAs0lIbHwkB81VxDQE=
-github.com/ceph/go-ceph v0.20.0 h1:weYE7zoVrIBk9bIVq8jS9z3RukGlnZwFGCth7Tu1ssU=
-github.com/ceph/go-ceph v0.20.0/go.mod h1:/4iZyaN5wTpIFMEKO6GU3xX3vHnyvd2Fcdf05n9VuD0=
+github.com/ceph/go-ceph v0.21.0 h1:nx+6FARWQqQ3ctSVwljeeauh0wgyVvd17i23d75mpA8=
+github.com/ceph/go-ceph v0.21.0/go.mod h1:574HYNbG0RZV7lBemoCIxrQEUlo/1BzN42y5NgDr4vg=
 github.com/certifi/gocertifi v0.0.0-20191021191039-0944d244cd40/go.mod h1:sGbDF6GwGcLpkNXPUTkMRoywsNa/ol15pxFe6ERfguA=
 github.com/certifi/gocertifi v0.0.0-20200922220541-2c3bb06c6054/go.mod h1:sGbDF6GwGcLpkNXPUTkMRoywsNa/ol15pxFe6ERfguA=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=