Update minio/mc Docker tag to v2021

This MR contains the following updates:

Package	Type	Update	Change
minio/mc	ironbank-docker	major	RELEASE.2020-11-25T23-04-07Z -> RELEASE.2021-01-05T05-03-58Z
minio/mc		major	RELEASE.2020-11-25T23-04-07Z -> RELEASE.2021-01-05T05-03-58Z
minio/mc	stage	major	RELEASE.2020-11-25T23-04-07Z -> RELEASE.2021-01-05T05-03-58Z

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