Update bash

Changes:

- https://github.com/tianon/docker-bash/commit/b589273: Update devel to 20201214, commit 975643bb2b3c00f4f57d77a53cc0e00d31e52cf1

library/bash

@@ -3,9 +3,9 @@
 Maintainers: Tianon Gravi <[email protected]> (@tianon)
 GitRepo: https://github.com/tianon/docker-bash.git
 
-Tags: devel-20201128, devel
+Tags: devel-20201214, devel
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
-GitCommit: bc28cc2452049074a182cb3f379b8ce810cc46c2
+GitCommit: b589273a1d10b1a3f994843f3cd3943f8fdbba68
 Directory: devel
 
 Tags: 5.1.0, 5.1, 5, latest