Update ghost

Changes:

- https://github.com/docker-library/ghost/commit/8d6ccd9: Update to 4.12.1, ghost-cli 1.17.3

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: 4.12.0, 4.12, 4, latest
+Tags: 4.12.1, 4.12, 4, latest
 Architectures: amd64, arm32v7, arm64v8, ppc64le, s390x
-GitCommit: 1908a3f3319e1ae4b72e1e4aedfc04d3a52bc780
+GitCommit: 8d6ccd98654b78b43494b248074137550cd1a11b
 Directory: 4/debian
 
-Tags: 4.12.0-alpine, 4.12-alpine, 4-alpine, alpine
+Tags: 4.12.1-alpine, 4.12-alpine, 4-alpine, alpine
 Architectures: amd64, arm32v6, arm32v7, arm64v8
-GitCommit: 1908a3f3319e1ae4b72e1e4aedfc04d3a52bc780
+GitCommit: 8d6ccd98654b78b43494b248074137550cd1a11b
 Directory: 4/alpine
 
 Tags: 3.42.5, 3.42, 3