Provide better errors for unsupported event types (#68)

* Validate event type during restore

* PR Feedback

* Format

* Linting

src/constants.ts

@@ -12,3 +12,9 @@ export enum State {
     CacheKey = "CACHE_KEY",
     CacheResult = "CACHE_RESULT"
 }
+
+export enum Events {
+    Key = "GITHUB_EVENT_NAME",
+    Push = "push",
+    PullRequest = "pull_request"
+}