chore: ignore the Android keystore

See https://docs.godotengine.org/en/stable/getting_started/workflow/export/exporting_for_android.html#create-a-debug-keystore
to generate one if you need to.

.gitignore

@@ -1,12 +1,12 @@
-
 # Godot
 .imports/*
 .import/*
 .test/
 tests/results/*
 
-# Hmmm…
+# Android
 android/build/
+debug.keystore
 
 # OS
 .directory