[WIP] feat: updated workflow files to use checkout@v2

[mikemimik]

What / Why

WIP - testing

References

• Related to CI: switch to actions/checkout@v2 #600

[npm-deploy-user]

	angular-quickstart			app-large			app-medium			ember-quickstart			react-app
	prev	current	status	prev	current	status	prev	current	status	prev	current	status	prev	current	status
initial install	38.3s	40s	✅🐌	36.7s	38.6s	✅🐌	32.4s	33.9s	✅🐌	26.3s	26.7s	✅🐌	30.6s	32.6s	✅🐌
repeat install	8.7s	9.4s	✅🐌	8.9s	8.5s	✅	8s	9.9s	🛑	6.9s	7.4s	✅🐌	8.4s	8.9s	✅🐌
with warm cache	29.1s	31.2s	✅🐌	31.7s	33.8s	✅🐌	27.2s	30.1s	✅🐌	22.4s	23.8s	✅🐌	26.9s	28.3s	✅🐌
with node_modules	8.6s	8.8s	✅🐌	7.7s	8s	✅🐌	8s	8.3s	✅🐌	6.9s	7.5s	✅🐌	8.3s	9.2s	✅🐌
with lockfile	27.3s	29.2s	✅🐌	31.5s	31.7s	✅🐌	28.9s	29.4s	✅🐌	19.3s	21.9s	🛑	24.3s	26.5s	✅🐌
with warm cache and node_modules	9s	9.1s	✅🐌	8.4s	7.8s	✅	8s	8.8s	✅🐌	7.1s	7.4s	✅🐌	8.4s	9s	✅🐌
with warm cache and lockfile	22.8s	24.3s	✅🐌	24.8s	26.6s	✅🐌	23.2s	24.7s	✅🐌	15.5s	16.7s	✅🐌	20.4s	21.4s	✅🐌
with node_modules and lockfile	9.3s	10s	✅🐌	8.6s	8.8s	✅🐌	8.6s	8.7s	✅🐌	7.3s	7.5s	✅🐌	9.2s	9.4s	✅🐌