fix: casbin migration

failed to initialize rbac:
error creating rbac enforcer: invalid policy rule size: expected 6, got 5,
rule: [everyone database.kratos * deny true]

setting v5 as empty string didn't fix this.
Casbin probably still sees the row as 5 columns, so setting it as "na".

Policies formed from permissions table have a valid UUID for v5 and mission-control uses uuid.Validate() to filter them out.

views/031_casbin_effect.sql

@@ -1,3 +1,5 @@
 UPDATE casbin_rule SET v3 = 'allow' WHERE ptype = 'p' and (v3 is null or v3 = '');
 
-UPDATE casbin_rule SET v4 = 'true' WHERE ptype = 'p' and (v4 is null OR v4 = '');
+UPDATE casbin_rule SET v4 = 'true' WHERE ptype = 'p' and (v4 is null OR v4 = '');
+
+UPDATE casbin_rule SET v5 = 'na' WHERE ptype = 'p' and (v5 is null OR v5 = '');