build(pre-commit): cache eslint in pre-commit

Run eslint with `--cache` to speed up pre-commit scripts.

This was added to the `pnpm run lint` script in
b7f9495a (build: add eslint --cache file, 2022-08-27)
and doesn't seem to be causing any issues.

I haven't enabled `--cache` for `prettier` since as of prettier 2.8.0,
their cache invalidation doesn't yet work with prettier plugins.

.lintstagedrc.mjs

@@ -1,5 +1,11 @@
 export default {
-  '!(docs/**/*)*.{ts,js,json,html,md,mts}': ['eslint --fix', 'prettier --write'],
+  '!(docs/**/*)*.{ts,js,json,html,md,mts}': [
+    'eslint --cache --cache-strategy content --fix',
+    // don't cache prettier yet, since we use `prettier-plugin-jsdoc`,
+    // and prettier doesn't invalidate cache on plugin updates"
+    // https://prettier.io/docs/en/cli.html#--cache
+    'prettier --write',
+  ],
   'cSpell.json': ['ts-node-esm scripts/fixCSpell.ts'],
   '**/*.jison': ['pnpm -w run lint:jison'],
 };