build: switched from jarsigner to apksigner

scripts/sign_apk.sh

@@ -21,13 +21,20 @@ if [ -z $JKS_KEYPASS ]; then
     exit 1
 fi
 
+# Zipalign
+zipalign=$(find $ANDROID_HOME/build-tools -name "zipalign" -print | head -n 1)
+$zipalign -v 4 $input $input.new
+mv $input.new $input
+
 # Sign
-jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 \
-    -storepass $JKS_STOREPASS -keypass $JKS_KEYPASS \
-    -keystore android.jks $input activitywatch
-jarsigner -verify $input
-mv $input $output
+# Using apksigner instead of jarsigner since API 30+: https://stackoverflow.com/a/69473649
+apksigner=$(find $ANDROID_HOME/build-tools -name "apksigner" -print | head -n 1)
+$apksigner sign --ks android.jks --ks-key-alias activitywatch \
+    --ks-pass env:JKS_STOREPASS --key-pass env:JKS_KEYPASS \
+    $input
 
-zipalign=$(find $ANDROID_HOME/build-tools -name "zipalign" -print | head -n 1)
-$zipalign -v 4 $output $output.new
-mv $output.new $output
+# Verify
+$apksigner verify $input
+
+# Move to output destination
+mv $input $output