Update heroku go to v5

[davidji99]

Basically a clone of #196.

[davidji99]

Hi @mars,

Please review. I have a dependency on the provider using heroku-go v5 so I cherry-picked your 6c6cb76 and ran go mod tidy and go mod vendor again.

[mars]

Looks good @davidji99 😄 Thanks for taking care of this!

I just started a Hashicorp CI run ⏳Will report back.

[mars]

Hashicorp CI ran out of Private Spaces, so I’ll have to clean-up the cruft & re-run later this morning.

[mars]

The CI run failed 1 test 🙅‍♂️

------- Stdout: -------
=== RUN   TestAccDatasourceHerokuApp_Basic
--- FAIL: TestAccDatasourceHerokuApp_Basic (10.54s)
    testing.go:538: Step 1 error: Check failed: Check 7/9 error: data.heroku_app.foobar: Attribute 'buildpacks.0' expected "https://github.com/heroku/heroku-buildpack-multi-procfile", got "heroku/go"
FAIL

[davidji99]

The CI run failed 1 test 🙅‍♂️

------- Stdout: -------
=== RUN   TestAccDatasourceHerokuApp_Basic
--- FAIL: TestAccDatasourceHerokuApp_Basic (10.54s)
    testing.go:538: Step 1 error: Check failed: Check 7/9 error: data.heroku_app.foobar: Attribute 'buildpacks.0' expected "https://github.com/heroku/heroku-buildpack-multi-procfile", got "heroku/go"
FAIL

Thanks will take a look.

[davidji99]

@mars Will you run the full suite again? I updated this branch to use heroku-go v5.1.0.

[mars]

Running the suite now 🏃‍♂️

[davidji99]

Thanks!

[mars]

After some normal flakiness, the Hashicorp CI passed for this PR ✅