fix(cli) tie example apps to package version

[xavdid]

Previously, all versions of the CLI pulled from the master branch when making example apps. This was good because we could fixes to the example apps would be available right away. Less good because example apps might conflict with released versions of the CLI.

This came to a head when I merged #124 and the build broke. Two main issues:

• Part of the build is calling zapier init --template typescript and zapier build. Now, this test was running using the master branch's typescript template but published core@9.0.0. Because that PR changed the TS configuration, the definitions in core were incompatible and it threw an error.
• apparently CI isn't run on PRs of forks. There's good reason for this, but I didn't realize that was the case and merged a bad change.

Pinning examples to releases means slower bug fixes (which are infrequent anyway), but more control (and the ability to make breaking changes in the templates without affecting versions in the wild).

[eliangcs]

The code looks good! I didn't test as I assume you already did.