fix incorrect volatile sql function type

hive/db/sql_scripts/bridge_get_ranked_post_for_observer_communities.sql

@@ -55,7 +55,7 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;
 
 DROP FUNCTION IF EXISTS bridge_get_ranked_post_by_hot_for_observer_communities;
 CREATE FUNCTION bridge_get_ranked_post_by_hot_for_observer_communities( in _observer VARCHAR, in _author VARCHAR, in _permlink VARCHAR, in _limit SMALLINT )
@@ -118,7 +118,7 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;
 
 DROP FUNCTION IF EXISTS bridge_get_ranked_post_by_payout_comments_for_observer_communities;
 CREATE FUNCTION bridge_get_ranked_post_by_payout_comments_for_observer_communities( in _observer VARCHAR,  in _author VARCHAR, in _permlink VARCHAR, in _limit SMALLINT )
@@ -190,7 +190,7 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;
 
 DROP FUNCTION IF EXISTS bridge_get_ranked_post_by_payout_for_observer_communities;
 CREATE FUNCTION bridge_get_ranked_post_by_payout_for_observer_communities( in _observer VARCHAR, in _author VARCHAR, in _permlink VARCHAR, in _limit SMALLINT )
@@ -255,7 +255,7 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;
 
 DROP FUNCTION IF EXISTS bridge_get_ranked_post_by_promoted_for_observer_communities;
 CREATE FUNCTION bridge_get_ranked_post_by_promoted_for_observer_communities( in _observer VARCHAR, in _author VARCHAR, in _permlink VARCHAR, in _limit SMALLINT )
@@ -318,7 +318,7 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;
 
 DROP FUNCTION IF EXISTS bridge_get_ranked_post_by_trends_for_observer_communities;
 CREATE OR REPLACE FUNCTION bridge_get_ranked_post_by_trends_for_observer_communities( in _observer VARCHAR, in _author VARCHAR, in _permlink VARCHAR, in _limit SMALLINT )
@@ -390,7 +390,7 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;
 
 DROP FUNCTION IF EXISTS bridge_get_ranked_post_by_muted_for_observer_communities;
 CREATE FUNCTION bridge_get_ranked_post_by_muted_for_observer_communities( in _observer VARCHAR, in _author VARCHAR, in _permlink VARCHAR, in _limit SMALLINT )
@@ -454,4 +454,4 @@ BEGIN
   LIMIT _limit;
 END
 $function$
-language plpgsql VOLATILE;
+language plpgsql STABLE;