Update ghost

Changes:

- https://github.com/docker-library/ghost/commit/20f003a: Update to 3.12.1, ghost-cli 1.13.1

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: 3.12.0, 3.12, 3, latest
+Tags: 3.12.1, 3.12, 3, latest
 Architectures: amd64, arm32v7, arm64v8, ppc64le, s390x
-GitCommit: 698b7407674e87fc0519d173e7da877e02171e71
+GitCommit: 20f003a55d1b52efa436df1981852155e8f418c0
 Directory: 3/debian
 
-Tags: 3.12.0-alpine, 3.12-alpine, 3-alpine, alpine
+Tags: 3.12.1-alpine, 3.12-alpine, 3-alpine, alpine
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
-GitCommit: 698b7407674e87fc0519d173e7da877e02171e71
+GitCommit: 20f003a55d1b52efa436df1981852155e8f418c0
 Directory: 3/alpine
 
 Tags: 2.38.0, 2.38, 2