Use render! in benchmarks to avoid making it faster by breaking things.

@camilo & @arthurnn for review

## Problem

When making breaking changes, we need to make sure to update the benchmarks along with the code.  Without this change, we might think a change makes the code faster, when actually it just skips code by exceptions being raised, caught, and rendered.

## Solution

Use Template#render! in the benchmarks so that we don't catch exceptions during rendering.