Switch care_map_generator.py to Python 3.

This is the last remaining use of the python-symbol library
from Python 2.

Test: Ran 2to3 on the script, no changes reported.
Change-Id: I9c8bf4840eaf1832cabc4b6af831f5c2de554d4f
diff --git a/update_verifier/Android.bp b/update_verifier/Android.bp
index f9a8341..ff2eff9 100644
--- a/update_verifier/Android.bp
+++ b/update_verifier/Android.bp
@@ -121,12 +121,12 @@
 
     version: {
         py2: {
-            enabled: true,
-            embedded_launcher: true,
-        },
-        py3: {
             enabled: false,
             embedded_launcher: false,
         },
+        py3: {
+            enabled: true,
+            embedded_launcher: true,
+        },
     },
 }