[automerger skipped] Bump minSdk to 21 am: 4b893fefe5 -s ours

am skip reason: Merged-In I080e1ab31139379423e74e44ff3fa76b36becbb3 with SHA-1 1448a452b5 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/setupcompat/+/27187010

Change-Id: Icaf528296be8147dcc2f30bf29e08760589f1430
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>