Update drupal

Changes:

- https://github.com/docker-library/drupal/commit/d560abe: Update to 8.7.7
- https://github.com/docker-library/drupal/commit/d50dbfe: Update generated README

library/drupal

@@ -4,19 +4,19 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/drupal.git
 
-Tags: 8.7.6-apache, 8.7-apache, 8-apache, apache, 8.7.6, 8.7, 8, latest
+Tags: 8.7.7-apache, 8.7-apache, 8-apache, apache, 8.7.7, 8.7, 8, latest
 Architectures: amd64, arm32v5, arm32v7, arm64v8, i386, ppc64le
-GitCommit: 4a5014c81c582cdb6e0d18a479d8645642700c69
+GitCommit: d560abe7847e839f6a130c37605966e160f3ac88
 Directory: 8.7/apache
 
-Tags: 8.7.6-fpm, 8.7-fpm, 8-fpm, fpm
+Tags: 8.7.7-fpm, 8.7-fpm, 8-fpm, fpm
 Architectures: amd64, arm32v5, arm32v7, arm64v8, i386, ppc64le
-GitCommit: 4a5014c81c582cdb6e0d18a479d8645642700c69
+GitCommit: d560abe7847e839f6a130c37605966e160f3ac88
 Directory: 8.7/fpm
 
-Tags: 8.7.6-fpm-alpine, 8.7-fpm-alpine, 8-fpm-alpine, fpm-alpine
+Tags: 8.7.7-fpm-alpine, 8.7-fpm-alpine, 8-fpm-alpine, fpm-alpine
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le
-GitCommit: 4a5014c81c582cdb6e0d18a479d8645642700c69
+GitCommit: d560abe7847e839f6a130c37605966e160f3ac88
 Directory: 8.7/fpm-alpine
 
 Tags: 8.6.17-apache, 8.6-apache, 8.6.17, 8.6