Incorrect spell slot being consumed

[RainbowEncoder]

Describe the bug
When casting a spell with multiple levels of spell slots available the spell is cast as if you selected the next level up.

To Reproduce

1. Have a spell caster character with multiple spell slot levels available
2. Cast a spell below the highest level
3. In the Cast Spell dialogue select a spell slot below the highest and confirm

Expected behaviour
The spell is cast using the selected spell slot at the selected level

Technical details

• OS: Windows 10
• Browser: Vivaldi (Chromium-based)
• Foundry Version: v11.308
• SFRPG Version: v0.25.2

Additional context
My own investigations pointed to a change in the spell-cast.hbs to fix Pre-select triggered level for variable level spell #664

That incremented the values of the select options of the Spell Slot selector menu by one. However within actor.js it assumes that the value from the select will be a 0-based index of available spell slots but it's now returning a 1-based index. Thus it's treating it as if you choose the next level of spell slot.

I think the cause of the confusion is that it's trying to set the default by spell level but the values are an index and not spell level but for a level 1+ variable spell a 1-based index and spell level would align