added warning system

Co-authored-by: Ajay Ramachandran <dev@ajay.app>

databases/_upgrade_sponsorTimes_4.sql

@@ -0,0 +1,12 @@
+BEGIN TRANSACTION;
+
+/* Create warnings table */
+CREATE TABLE "warnings" (
+    userID TEXT NOT NULL,
+    issueTime INTEGER NOT NULL,
+    issuerUserID TEXT NOT NULL
+);
+
+UPDATE config SET value = 4 WHERE key = "version";
+
+COMMIT;