replace deprecated get_element() which was removed in 4.x

/usr/lib/python3/dist-packages/androguard/core/bytecodes/apk.py:884: DeprecationWarning: This method is deprecated since 3.3.5.

It was added in 3.3.5.  Debian/bullseye and Ubuntu/20.04/focal both include
new enough versions.  Debian/buster's is too old (3.3.3).

fdroidserver/update.py

@@ -1627,7 +1627,7 @@ def scan_apk_androguard(apk, apkfile):
     if maxSdkVersion is not None:
         apk['maxSdkVersion'] = maxSdkVersion
 
-    icon_id_str = apkobject.get_element("application", "icon")
+    icon_id_str = apkobject.get_attribute_value("application", "icon")
     if icon_id_str:
         try:
             icon_id = int(icon_id_str.replace("@", "0x"), 16)

setup.py

@@ -92,7 +92,7 @@ setup(
     ],
     install_requires=[
         'appdirs',
-        'androguard >= 3.3.3',
+        'androguard >= 3.3.5',
         'clint',
         'defusedxml',
         'GitPython',