fix/migrate broken embedding columns (getzep#256)

* move migrations to after table creation

* actually commit migrations

pkg/store/postgres/migrations/2023110100_add_missing_embedding_column.down.sql

@@ -0,0 +1,4 @@
+/* Intentionally left blank as we don't want to remove an 
+    embedding column that was potentially already there before the up 
+*/
+

pkg/store/postgres/migrations/2023110100_add_missing_embedding_column.up.sql

@@ -0,0 +1,29 @@
+DO $$
+BEGIN
+    IF EXISTS(
+        SELECT
+        FROM
+            pg_tables
+        WHERE
+            tablename = 'message_embedding') THEN
+    ALTER TABLE message_embedding
+        ADD COLUMN IF NOT EXISTS embedding vector(1536);
+END IF;
+END
+$$;
+
+
+DO $$
+BEGIN
+    IF EXISTS(
+        SELECT
+        FROM
+            pg_tables
+        WHERE
+            tablename = 'summary_embedding') THEN
+    ALTER TABLE summary_embedding
+        ADD COLUMN IF NOT EXISTS embedding vector(1536);
+END IF;
+END
+$$;
+