`gatsby develop` page reloads fail if URL ends with a SemVer range

[danoc]

Hi! This is a weird one.

gatsby develop uses parse-filepath to grab the extension from a URL and serve public/index.html:

gatsby/packages/gatsby/src/commands/develop.js

Lines 146 to 158 in b21a022

	// Render an HTML page and serve it.
	app.use((req, res, next) => {
	const parsedPath = parsePath(req.path)
	if (parsedPath.extname === `` || parsedPath.extname.startsWith(`.html`)) {
	res.sendFile(directoryPath(`public/index.html`), err => {
	if (err) {
	res.status(500).end()
	}
	})
	} else {
	next()
	}
	})

Line 149 incorrectly fails for our URLs that include a SemVer range at the end.

This happens because parse-filepath believes that a URL like /tp-ui-react-button/1.6.3/ has a file extension of .3:

This causes the development server to throw a 404 when attempting to reload the page: "Cannot GET /tp-ui-react-button/1.6.3/". The reloads work when I use URLs that end in index.html

---

I'll likely work around this by wrapping gatsby-link to append index.html to URLs on development.

Any thoughts on adding parsedPath.path.endsWith('/') to the conditional on L149? I can make the change if y'all would like.

[calcsam]

Sure, definitely add a PR w/ a test case.