Update ghost

Changes:

- https://github.com/docker-library/ghost/commit/819c182: Update to 5.2.1, ghost-cli 1.21.0
- https://github.com/docker-library/ghost/commit/67269d3: Merge pull request https://github.com/docker-library/ghost/pull/312 from infosiftr/virtual
- https://github.com/docker-library/ghost/commit/d934156: Update to 5.2.0, ghost-cli 1.21.0
- https://github.com/docker-library/ghost/commit/ae52dd8: Golf down the virtual declaration to avoid "ERROR: No such package: .build-deps-sharp"
- https://github.com/docker-library/ghost/commit/c91b1df: Merge pull request https://github.com/docker-library/ghost/pull/308 from infosiftr/arm64+

library/ghost

@@ -4,14 +4,14 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/ghost.git
 
-Tags: 5.1.1, 5.1, 5, latest
+Tags: 5.2.1, 5.2, 5, latest
 Architectures: amd64, arm32v7, arm64v8, ppc64le, s390x
-GitCommit: b72aca608fbecd57cf7692b1cbf0786b18403e05
+GitCommit: 819c182bcd91512d5d84201ef01346b2b9f46b5e
 Directory: 5/debian
 
-Tags: 5.1.1-alpine, 5.1-alpine, 5-alpine, alpine
+Tags: 5.2.1-alpine, 5.2-alpine, 5-alpine, alpine
 Architectures: amd64, arm32v6, arm32v7, arm64v8
-GitCommit: b72aca608fbecd57cf7692b1cbf0786b18403e05
+GitCommit: 819c182bcd91512d5d84201ef01346b2b9f46b5e
 Directory: 5/alpine
 
 Tags: 4.48.1, 4.48, 4