Fix heredoc syntax in circle.yml

> bash: line 11: warning: here-document at line 2 delimited by end-of-file (wanted `EOF')
> bash: -c: line 12: syntax error: unexpected end of file

https://198-598343-gh.circle-artifacts.com/0//tmp/circle-artifacts.pvRwaTX/stderr_mkdir_16907.txt
diff --git a/circle.yml b/circle.yml
index 4bc040a..6f1dde9 100644
--- a/circle.yml
+++ b/circle.yml
@@ -84,7 +84,7 @@
           })
           .listen(9000);
           console.error('listening on http://0.0.0.0:9000/');
-          EOF
+        EOF
         } >$CIRCLE_TEST_REPORTS/mocha/xunit.xml 2>$CIRCLE_ARTIFACTS/mocha-test-report.log
       :
         background: true