Add github-actions bot (#1466)

See https://github.com/sourcecred/sourcecred-action/pull/6
as an example of the bot acting as a user.

src/plugins/github/blacklistedObjectIds.js

@@ -60,6 +60,7 @@ export const BLACKLISTED_IDS: $ReadOnlyArray<ObjectId> = deepFreeze([
   "MDM6Qm90Mjk5NjY3OTc=", // eslint
   "MDM6Qm90Mjc4NTYyOTc=", // dependabot-preview
   "MDM6Qm90MzY3NzE0MDE=", // azure-pipelines
+  "MDM6Qm90NDE4OTgyODI=", // github-actions
 
   // Problematic interactions they did as a user: reactions.
   "MDg6UmVhY3Rpb24yMTY3ODkyNQ==",

src/plugins/github/bots.js

@@ -19,5 +19,6 @@ export function botSet(): Set<string> {
     "tensorflow-gardener",
     "tensorflow-jenkins",
     "tensorflowbutler",
+    "github-actions",
   ]);
 }