Update mariadb

Changes:

- https://github.com/docker-library/mariadb/commit/5b833d3: Update to 1:10.3.16+maria~bionic
- https://github.com/docker-library/mariadb/commit/f2ecbc3: Update to 1:10.2.25+maria~bionic
- https://github.com/docker-library/mariadb/commit/a7596ce: Update generated README

library/mariadb

@@ -9,14 +9,14 @@ Architectures: amd64, arm64v8, ppc64le
 GitCommit: c969655b3c92a1ae3f066e506ab7b32ff4ba4582
 Directory: 10.4
 
-Tags: 10.3.15-bionic, 10.3-bionic, 10-bionic, bionic, 10.3.15, 10.3, 10, latest
+Tags: 10.3.16-bionic, 10.3-bionic, 10-bionic, bionic, 10.3.16, 10.3, 10, latest
 Architectures: amd64, arm64v8, ppc64le
-GitCommit: c969655b3c92a1ae3f066e506ab7b32ff4ba4582
+GitCommit: 5b833d3bb53298adea162c555f066233f74ff236
 Directory: 10.3
 
-Tags: 10.2.24-bionic, 10.2-bionic, 10.2.24, 10.2
+Tags: 10.2.25-bionic, 10.2-bionic, 10.2.25, 10.2
 Architectures: amd64, arm64v8, ppc64le
-GitCommit: c969655b3c92a1ae3f066e506ab7b32ff4ba4582
+GitCommit: f2ecbc37bcca1c61a2154dd8c677fb17504d443c
 Directory: 10.2
 
 Tags: 10.1.40-bionic, 10.1-bionic, 10.1.40, 10.1