sim: Update Linaro copyrights

Update to current year for files modified.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/mcuboot-sys/src/api.rs b/sim/mcuboot-sys/src/api.rs
index 8d1140d..fb55595 100644
--- a/sim/mcuboot-sys/src/api.rs
+++ b/sim/mcuboot-sys/src/api.rs
@@ -1,4 +1,4 @@
-// Copyright (c) 2017-2019 Linaro LTD
+// Copyright (c) 2017-2021 Linaro LTD
 // Copyright (c) 2018-2019 JUUL Labs
 //
 // SPDX-License-Identifier: Apache-2.0