fix: pass right apply context (#100)

Reading the source code, I've noticed that:

```js
(this.values || this.bind).push.apply(this.values, statement.values)
  ^ if this is falsy                   ^ so is this one
```

This fix makes the code not fail when `useBind` and `append` are used in the wild.

index.js

@@ -28,7 +28,8 @@ class SQLStatement {
     if (statement instanceof SQLStatement) {
       this.strings[this.strings.length - 1] += statement.strings[0]
       this.strings.push.apply(this.strings, statement.strings.slice(1))
-      ;(this.values || this.bind).push.apply(this.values, statement.values)
+      const list = this.values || this.bind
+      list.push.apply(list, statement.values)
     } else {
       this.strings[this.strings.length - 1] += statement
     }