Implement first custom linter rule async-suffix

packages/dev-utils/src/blockchain_lifecycle.ts

@@ -20,7 +20,4 @@ export class BlockchainLifecycle {
             throw new Error(`Snapshot with id #${snapshotId} failed to revert`);
         }
     }
-    public async mineABlock(): Promise<void> {
-        await this.rpc.mineBlockAsync();
-    }
 }