fix: support cjs modules when loading typography config

[Sekhmet]

Description

After PR #10545 typography is loaded using require(...).default:

gatsby/packages/gatsby-plugin-typography/src/gatsby-browser.js

Lines 12 to 13 in 93bf83b

	// typography links to the file set in "pathToConfigModule"
	typography = require(`./.cache/typography.js`).default

It works with custom configs (which are ES6 modules), but it doesn't work with CommonJS modules.
Default config uses CommonJS export:

gatsby/packages/gatsby-plugin-typography/src/gatsby-node.js

Lines 19 to 23 in 93bf83b

	} else {
	module = `const Typography = require("typography")
	const typography = new Typography()
	module.exports = typography`
	}

This is why typography is not properly loaded and page crashes on load when using default config.

Related Issues

Fixes #10609

[LekoArts]

Ah, good catch. I didn't think of testing that as it never occurred to me that someone tells you to use it without a config. The package README itself doesn't mention that 😆

Thanks for the fix 👍