Set minSdkVersion via our SupportAndroidLibraryPlugin.

Test: ./gradlew assembleAndroidTest in support and app-toolkit
Change-Id: I61ae66020bc32e638a7d5e15b5994d986fb14d7d
diff --git a/tv-provider/build.gradle b/tv-provider/build.gradle
index eb5d297..c7d7c8a 100644
--- a/tv-provider/build.gradle
+++ b/tv-provider/build.gradle
@@ -13,12 +13,6 @@
     androidTestImplementation(TEST_RUNNER, libs.exclude_annotations)
 }
 
-android {
-    defaultConfig {
-        minSdkVersion 21
-    }
-}
-
 supportLibrary {
     name = "Android Support TV Provider"
     publish = true
@@ -27,4 +21,5 @@
     inceptionYear = "2017"
     description = "Android Support Library for TV Provider"
     legacySourceLocation = true
+    minSdkVersion = 21
 }
\ No newline at end of file