Update bash

Changes:

- https://github.com/tianon/docker-bash/commit/9fc0cdf: Update devel to 20200921, commit ef70f295bc396e6eb1e8245cfe896b5ad070d91f

library/bash

@@ -3,9 +3,9 @@
 Maintainers: Tianon Gravi <[email protected]> (@tianon)
 GitRepo: https://github.com/tianon/docker-bash.git
 
-Tags: devel-20200914, devel
+Tags: devel-20200921, devel
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
-GitCommit: 54576355cdfa2bd4b2e0f68ad4a00bd4d00dd6e4
+GitCommit: 9fc0cdf3d999dfe38bc4d07f73b2b0d83653dde3
 Directory: devel
 
 Tags: 5.1-beta, 5.1-rc, rc