Update golang

Changes:

- https://github.com/docker-library/golang/commit/b9cdd8a: Merge pull request https://github.com/docker-library/golang/pull/350 from infosiftr/1.16-rc
- https://github.com/docker-library/golang/commit/2d03ce7: Add 1.16beta1

library/golang

@@ -5,6 +5,38 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Johan Euphrosine <[email protected]> (@proppy)
 GitRepo: https://github.com/docker-library/golang.git
 
+Tags: 1.16beta1-buster, 1.16-rc-buster, rc-buster
+SharedTags: 1.16beta1, 1.16-rc, rc
+Architectures: amd64, arm32v5, arm32v7, arm64v8, i386, mips64le, ppc64le, s390x
+GitCommit: 2d03ce7ef01477465c84c13d68818ab2bedc7b16
+Directory: 1.16-rc/buster
+
+Tags: 1.16beta1-alpine3.12, 1.16-rc-alpine3.12, rc-alpine3.12, 1.16beta1-alpine, 1.16-rc-alpine, rc-alpine
+Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
+GitCommit: 2d03ce7ef01477465c84c13d68818ab2bedc7b16
+Directory: 1.16-rc/alpine3.12
+
+Tags: 1.16beta1-windowsservercore-1809, 1.16-rc-windowsservercore-1809, rc-windowsservercore-1809
+SharedTags: 1.16beta1-windowsservercore, 1.16-rc-windowsservercore, rc-windowsservercore, 1.16beta1, 1.16-rc, rc
+Architectures: windows-amd64
+GitCommit: 2d03ce7ef01477465c84c13d68818ab2bedc7b16
+Directory: 1.16-rc/windows/windowsservercore-1809
+Constraints: windowsservercore-1809
+
+Tags: 1.16beta1-windowsservercore-ltsc2016, 1.16-rc-windowsservercore-ltsc2016, rc-windowsservercore-ltsc2016
+SharedTags: 1.16beta1-windowsservercore, 1.16-rc-windowsservercore, rc-windowsservercore, 1.16beta1, 1.16-rc, rc
+Architectures: windows-amd64
+GitCommit: 2d03ce7ef01477465c84c13d68818ab2bedc7b16
+Directory: 1.16-rc/windows/windowsservercore-ltsc2016
+Constraints: windowsservercore-ltsc2016
+
+Tags: 1.16beta1-nanoserver-1809, 1.16-rc-nanoserver-1809, rc-nanoserver-1809
+SharedTags: 1.16beta1-nanoserver, 1.16-rc-nanoserver, rc-nanoserver
+Architectures: windows-amd64
+GitCommit: 2d03ce7ef01477465c84c13d68818ab2bedc7b16
+Directory: 1.16-rc/windows/nanoserver-1809
+Constraints: nanoserver-1809, windowsservercore-1809
+
 Tags: 1.15.6-buster, 1.15-buster, 1-buster, buster
 SharedTags: 1.15.6, 1.15, 1, latest
 Architectures: amd64, arm32v5, arm32v7, arm64v8, i386, mips64le, ppc64le, s390x