implement Staticman v3 API scheme

[VincentTam]

Staticman's docs have recently been updated. On GitHub, the new GitHub App authorization mechanism is preferred over the traditional GitHub bot as the former is more resistant to GitHub's API rate limit (c.f. Staticman issues 222, 227, 243, 255).

edulabs/assets/js/main.js

Lines 33 to 34 in 41d5e94

	if (err.status === 429) {
	console.log("Too many requests");

From the official guide, the format of Staticman v3's POST URL is

{STATICMAN_BASE_URL}/v3/entry/{GIT_PROVIDER}/{GIT_PROVIDER_USERNAME}/{REPO}/{BRANCH}/{property (optional)}

e.g.

https://staticmaninstance.herokuapp.com/v3/entry/github/eduardoboucas/staticman/gh-pages/comments

🔗 https://staticman.net/docs/getting-started.html