Android,tools: don't open zip file in binary mode

Zip files are always opened in binary mode and the
ctor doesn't accept "b" in the mode string.

RELNOTES: none
PiperOrigin-RevId: 164832193
diff --git a/tools/android/aar_embedded_jars_extractor.py b/tools/android/aar_embedded_jars_extractor.py
index 305d38a..fcdc301 100644
--- a/tools/android/aar_embedded_jars_extractor.py
+++ b/tools/android/aar_embedded_jars_extractor.py
@@ -47,7 +47,7 @@
 
 
 def main():
-  with zipfile.ZipFile(FLAGS.input_aar, "rb") as aar:
+  with zipfile.ZipFile(FLAGS.input_aar, "r") as aar:
     with open(FLAGS.output_singlejar_param_file, "wb") as singlejar_param_file:
       ExtractEmbeddedJars(aar, singlejar_param_file, FLAGS.output_dir)