android build: use "cryptography" instead of "pycryptodomex" fork

Electrum needs either "cryptography" or "pycrytodomex" (since #6014).
Previously we have been using a custom fork (of ours) of pycryptodomex,
now let's just use upstream "cryptography".

electrum/gui/kivy/tools/Dockerfile

@@ -163,7 +163,7 @@ RUN cd /opt \
     && cd python-for-android \
     && git remote add sombernight https://github.com/SomberNight/python-for-android \
     && git fetch --all \
-    && git checkout 5ab509ad41e2e56026174dffcf280cf1d14d54ca \
+    && git checkout 690a8ecc8d1c7f446d42f53a89af06c9a2d00e4e \
     && python3 -m pip install --user -e .
 
 # build env vars

electrum/gui/kivy/tools/buildozer.spec

@@ -23,9 +23,7 @@ source.exclude_dirs = bin, build, dist, contrib,
     electrum/tests,
     electrum/gui/qt,
     electrum/gui/kivy/tools,
-    electrum/gui/kivy/theming/light,
-    # exclude pycryptodomex built by make_packages; android needs custom version
-    packages/cryptodome
+    electrum/gui/kivy/theming/light
 # (list) List of exclusions using pattern matching
 source.exclude_patterns = Makefile,setup*
 
@@ -46,7 +44,7 @@ requirements =
     kivy==39c17457bae91baf8fe710dc989791e45879f136,
     libffi,
     libsecp256k1,
-    pycryptodomex==bfc1cca093a7344c9ed2b7c34bc560db6dca662a
+    cryptography
 
 # (str) Presplash of the application
 #presplash.filename = %(source.dir)s/gui/kivy/theming/splash.png