Dry-run allow to add labels and update the issues :/

[C0ZEN]

Describe your issue

This PR introduced an issue #463 regarding the dry-run.
The project doesn't have test covering the operations per run, so it's only an assumption based on my understanding of the current code.

Here is the lack of dry-run wrapper:

stale/src/classes/issues-processor.ts

Line 743 in b1da9e1

await this.client.issues.addLabels({

stale/src/classes/issues-processor.ts

Line 787 in b1da9e1

await this.client.issues.addLabels({

stale/src/classes/issues-processor.ts

Line 801 in b1da9e1

await this.client.issues.update({

And I think that this block should not be cancelled in a dry-run.

stale/src/classes/issues-processor.ts

Line 821 in b1da9e1

if (!this.options.debugOnly) {

Sorry!