Update test to use in memory database

SQLite supports a special file path, :memory: which uses
an in-memory database. Thus, we use that for the test.

app_test.go

@@ -1,24 +1,12 @@
 package main
 
 import (
-	"os"
-	"path"
 	"reflect"
 	"testing"
 )
 
 func TestInsertAndQueryData(t *testing.T) {
-	dbPath := path.Join(t.TempDir(), "app.db")
-
-	// we close the DB connection
-	// and remove the DB path explicitly for Windows
-	// https://github.com/practicalgo/go-sqlite-demo/actions/runs/5319761510/jobs/9632645015
-	t.Cleanup(func() {
-		db.Close()
-		os.RemoveAll(dbPath)
-	})
-
-	err := initDatabase(dbPath)
+	err := initDatabase(":memory:")
 	if err != nil {
 		t.Fatal("error initializing database: ", err)
 	}