Add increment test case

src/test/scala/minisql/context/sql/MirrorSqlContextSuite.scala

@@ -74,4 +74,15 @@ class MirrorSqlContextSuite extends munit.FunSuite {
       "UPDATE foo SET name = ?, id = ? WHERE id = 1"
     )
   }
+
+  test("Update/increment") {
+    val delta = 1
+    val o = testContext.io(
+      Foos.filter(_.id == 1).update(f => f.id -> (f.id + lift(delta)))
+    )
+    assertEquals(
+      o.sql,
+      "UPDATE foo SET id = (id + ?) WHERE id = 1"
+    )
+  }
 }