TalkBack: Don't lower minSdkVersion

We already have a version compatible with older Android in the repository anyway

metadata/com.google.android.accessibility.talkback.yml

@@ -34,9 +34,7 @@ Builds:
       - yes
     rm:
       - libs
-    prebuild:
-      - sed -i 's/minSdkVersion 26/minSdkVersion 21/' build.gradle
-      - sed -i 's/android:versionCode=/android:versionName="$$VERSION$$" android:versionCode=/'
+    prebuild: sed -i 's/android:versionCode=/android:versionName="$$VERSION$$" android:versionCode=/'
         src/main/AndroidManifest.xml
 
 AutoUpdateMode: Version %v