chore: add timestamp for no-link releases (#168)

Author: barjin

git-cliff-release/cliff.toml

@@ -21,7 +21,7 @@ body = """
 {% elif extra.unreleased_version %}\
     ## {{ extra.unreleased_version | trim_start_matches(pat="v") }} - **not yet released**
 {% elif version %}
-    ## {{ version | trim_start_matches(pat="v") }}
+    ## {{ version | trim_start_matches(pat="v") }} ({{ timestamp | date(format="%Y-%m-%d") }})
 {% else %}\
     ## Unreleased
 {% endif %}\