Make build_servers.id just generated by default

As to make it easier to set explicitly.

sqitch/deploy/alter_build_servers_id_default.sql

@@ -0,0 +1,13 @@
+-- Deploy guix-data-service:alter_build_servers_id_default to pg
+
+BEGIN;
+
+ALTER TABLE build_servers
+  ALTER COLUMN id
+  DROP identity;
+
+ALTER TABLE build_servers
+  ALTER COLUMN id
+  ADD generated by default as identity;
+
+COMMIT;

sqitch/revert/alter_build_servers_id_default.sql

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

sqitch/sqitch.plan

@@ -99,3 +99,4 @@ nar_indexes 2023-08-01T11:37:35Z Chris <chris@felis> # Add nar related indexes
 git_repositories_poll_interval 2023-10-08T20:36:09Z Chris <chris@felis> # Add git_repositories.poll_interval
 git_repositories_job_priority 2024-03-07T09:39:27Z Chris <chris@felis> # Add git_repositories.job_priority
 build_server_build_id_index 2024-09-07T17:42:28Z Chris <chris@felis> # Add index on builds.build_server_build_id
+alter_build_servers_id_default 2024-12-15T20:48:51Z Chris <chris@fang> # Alter build_servers id default

sqitch/verify/alter_build_servers_id_default.sql

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