Change nar_urls size to bigint

As some nars can be bigger than the size of an int.

sqitch/deploy/change_nar_urls_size_to_bigint.sql

@@ -0,0 +1,7 @@
+-- Deploy guix-data-service:change_nar_urls_size_to_bigint to pg
+
+BEGIN;
+
+ALTER TABLE nar_urls ALTER COLUMN file_size TYPE bigint USING file_size::bigint;
+
+COMMIT;

sqitch/revert/change_nar_urls_size_to_bigint.sql

@@ -0,0 +1,7 @@
+-- Revert guix-data-service:change_nar_urls_size_to_bigint from pg
+
+BEGIN;
+
+-- XXX Add DDLs here.
+
+COMMIT;

sqitch/sqitch.plan

@@ -33,3 +33,4 @@ nar_related_tables 2019-11-29T20:28:19Z Christopher Baines <mail@cbaines.net> #
 add_index_on_builds_derivation_file_name 2019-12-03T16:23:55Z   <chris@phact> # Add index on builds_derivation_file_name
 narinfo_fetch_record 2019-12-03T20:53:28Z   <chris@phact> # Add a table to describe fetching a narinfo
 change_nars_size_to_bigint 2019-12-04T21:24:21Z   <chris@phact> # Change nars.size to bigint
+change_nar_urls_size_to_bigint 2019-12-04T21:49:07Z   <chris@phact> # Change nar_urls.size to bigint

sqitch/verify/change_nar_urls_size_to_bigint.sql

@@ -0,0 +1,7 @@
+-- Verify guix-data-service:change_nar_urls_size_to_bigint on pg
+
+BEGIN;
+
+-- XXX Add verifications here.
+
+ROLLBACK;