FMRadio: Add exported flags in manifest

Targeting S+ (version 31 and above) requires an explicit value
for android:exported to be defined when intent filters are present.

Change-Id: I2ce2b2cd1dcd69e343ae8577587483b19d825fdc
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 82db26d..12a6f31 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -51,6 +51,7 @@
             android:label="@string/app_name"
             android:launchMode="standard"
             android:theme="@style/AppTheme"
+            android:exported="true"
             android:usesCleartextTraffic="false" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />