tox: v↑ NEO (1.9 -> 1.12)

NEO 1.9 was released in 2018 and is outdated by now. NEO 1.12 is
currently the latest NEO release.

tox.ini

@@ -22,7 +22,7 @@ deps    =
     # ZODB/test/util depends on mock starting from ZODB 5.5
     ZODB5:  mock
 
-    neo:    neoppod >= 1.9
+    neo:    neoppod >= 1.12
     # neo.tests also imports MySQLdb unconditionally
     neo:    mysqlclient