change min sdk back to 21 for ic launcher

Change-Id: Ie4655030838a651e2276d66ffa77189248b55f73

Author: alabiaga

app/build.gradle.kts

@@ -27,7 +27,7 @@ android {
 
     defaultConfig {
         applicationId = "com.example.platform"
-        minSdk = 26
+        minSdk = 21
         targetSdk = 36
         versionCode = 1
         versionName = "1.0"