Fixed a bug with postgresql and mysql migration folders as well as compilation warning related to it

src/NadekoBot/Migrations/Mysql/20220703194400_logwarns.cs

@@ -0,0 +1,25 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace NadekoBot.Migrations.Mysql
+{
+    public partial class logwarns : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<ulong>(
+                name: "logwarnsid",
+                table: "logsettings",
+                type: "bigint unsigned",
+                nullable: true);
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "logwarnsid",
+                table: "logsettings");
+        }
+    }
+}