Release 1.2.1

- Fixed the dictionary update card taking too long to reappear after
  cancelling a download (DownloadManager).
- Bump agp 9.3.0 -> 9.3.1; migrate the release build type from
  isMinifyEnabled/isShrinkResources/proguardFiles to
  optimization { enable = true } with keep rules moved to
  app/src/release/keepRules/proguard-rules.keep.

app/src/release/keepRules/proguard-rules.keep

@@ -0,0 +1,11 @@
+
+# Remove logging in release builds
+# Keep Log.w() and Log.e() for crash reporting, remove only verbose/debug/info
+-assumenosideeffects class android.util.Log {
+    public static *** d(...);
+    public static *** v(...);
+    public static *** i(...);
+}
+
+-keepattributes *Annotation*
+-keepattributes SourceFile, LineNumberTable