Fix typo [skip ci]

Author: BanzaiMan

lib/travis/worker/job/runner.rb

@@ -110,7 +110,7 @@ def cancel
         def check_config
           case payload["config"][:".result"]
           when "parse_error"
-            announce "\033[31;1mERROR\033[0m: An error occured while trying to parse your .travis.yml file.\n"
+            announce "\033[31;1mERROR\033[0m: An error occurred while trying to parse your .travis.yml file.\n"
             announce "  http://lint.travis-ci.org can check your .travis.yml.\n"
             announce "  Please make sure that the file is valid YAML.\n\n"
             # TODO: Remove all of this once we can actually error the build