Update F-Droid metadata for v1.2.2.3 (#483)

- Added Android Q compatibility by building with go1.13rc2 and NDK r20

fdroiddata/metadata/com.github.catfriend1.syncthingandroid.yml

@@ -900,9 +900,9 @@ Builds:
       - PATH="$PWD/go/bin:$PATH" gradle buildNative
     ndk: r19c
 
-  - versionName: 1.2.2.2
-    versionCode: 1020202
-    commit: v1.2.2.2
+  - versionName: 1.2.2.3
+    versionCode: 1020203
+    commit: v1.2.2.3
     submodules: true
     gradle:
       - yes
@@ -918,7 +918,15 @@ Builds:
       - PATH="$PWD/go/bin:$PATH" gradle buildNative
     ndk: r20
 
+MaintainerNotes: |-
+    The submodule in syncthing/src/github.com/syncthing/syncthing must be
+    pristine, as the version/release information is taken from git.
+    The ignored directory
+    syncthing/src/github.com/syncthing/syncthing/lib/model/testdata
+    contains pre-generated data for testing and is thus not involved in the build
+    process.
+
 AutoUpdateMode: Version v%v
 UpdateCheckMode: Tags ^v[a-z0-9.]*$
-CurrentVersion: 1.2.2.1
-CurrentVersionCode: 1020201
+CurrentVersion: 1.2.2.3
+CurrentVersionCode: 1020203