[release] fix typo in release workflow (#261)

Author: SylvainJuge

.github/workflows/pre-post-release.yml

@@ -22,7 +22,7 @@ on:
         type: string
         required: true
       pr_body:
-        description: : 'pull-request body'
+        description: 'pull-request body'
         type: string
         required: true