Looking in the Editor, this spell only lists Wizard for classes, which is incorrect. Bug report this.
It _should_ be available for the following:
Level alchemist 3, arcanist 3, bard 3, bloodrager 3, investigator 3, magus 3, skald 3, sorcerer 3, wizard 3
For reference if needed in the Bug Report:
https://www.aonprd.com/SpellDisplay....=Infuse%20Self (Official PRD)