Add feature of escaping params to Find function

This change was made based on a suggestion from
Raí Tamarindo (raitamarindo@gmail.com)

postgres.go

@@ -26,8 +26,9 @@ func (c Client) Find(
 	ctx context.Context,
 	item interface{},
 	query string,
+	params ...interface{},
 ) error {
-	it := c.db.Raw(query)
+	it := c.db.Raw(query, params...)
 	it.Scan(item)
 	return it.Error
 }

postgres_test.go

@@ -51,7 +51,7 @@ func TestFind(t *testing.T) {
 			tableName: "users",
 		}
 		u := User{}
-		err = c.Find(ctx, &u, `SELECT * FROM users WHERE name='Bia';`)
+		err = c.Find(ctx, &u, `SELECT * FROM users WHERE name=?;`, "Bia")
 
 		assert.Equal(t, err, nil)
 		assert.Equal(t, "Bia", u.Name)