Remove type variable T

[cgarling]

Type variable T not used in init_cacheval method, so removed

Checklist

• [x ] Appropriate tests were added
• [x ] Any code changes were done in a way that does not break public API
• [x ] All documentation related to code changes were updated
• [x ] The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• [ x] Any new documentation only uses public API

Additional context

Add any other context about the problem here.