Fix changelog typo for postStartTimeout

Signed-off-by: David Kwon <[email protected]>

Author: dkwon17

CHANGELOG.md

@@ -26,7 +26,7 @@ metadata:
   name: devworkspace-operator-config
 config:
   workspace:
-    postStartTimeout: 30 
+    postStartTimeout: '30s'
 ```
 By default, this timeout is disabled.