(data): Start migration v7 -> v8.

data/migration/v7-v8/migration.sql

@@ -0,0 +1,18 @@
+ALTER TABLE guild_config ADD COLUMN pomodoro_channel BIGINT;
+
+-- Timer Data {{{
+create TABLE timers(
+  channelid BIGINT PRIMARY KEY,
+  guildid BIGINT NOT NULL REFERENCES guild_config (guildid),
+  text_channelid BIGINT,
+  focus_length INTEGER NOT NULL,
+  break_length INTEGER NOT NULL,
+  last_started TIMESTAMPTZ NOT NULL,
+  inactivity_threshold INTEGER,
+  channel_name TEXT,
+  pretty_name TEXT
+);
+CREATE INDEX timers_guilds ON timers (guildid);
+-- }}}
+
+INSERT INTO VersionHistory (version, author) VALUES (8, 'v7-v8 migration');