android build: make sure to use correct pycryptodomex

note: buildozer casts all actual paths to lowercase but not the list of excluded paths...
see 182d13f102/buildozer/__init__.py (L775)

electrum/gui/kivy/tools/buildozer.spec

@@ -23,7 +23,9 @@ source.exclude_dirs = bin, build, dist, contrib,
     electrum/tests,
     electrum/gui/qt,
     electrum/gui/kivy/tools,
-    electrum/gui/kivy/theming/light
+    electrum/gui/kivy/theming/light,
+    # exclude pycryptodomex built by make_packages; android needs custom version
+    packages/cryptodome
 # (list) List of exclusions using pattern matching
 source.exclude_patterns = Makefile,setup*