chore(🤖): update DEFAULT_MIN_SDK_VERSION to its real value (#3076)

Author: wcandillon

packages/skia/android/build.gradle

@@ -19,7 +19,7 @@ import java.nio.file.Paths
 // the minimum React Native version supported.
 def DEFAULT_COMPILE_SDK_VERSION = 28
 def DEFAULT_BUILD_TOOLS_VERSION = '28.0.3'
-def DEFAULT_MIN_SDK_VERSION = 16
+def DEFAULT_MIN_SDK_VERSION = 21
 def DEFAULT_TARGET_SDK_VERSION = 28
 
 def safeExtGet(prop, fallback) {