doc news: update version number (#425)

Because We fail release of 4.0.3.

Author: komainu8

_po/ja/news/index.po

@@ -22,7 +22,7 @@ msgstr ""
 msgid "# News"
 msgstr "# おしらせ"
 
-msgid "## 4.0.3: 2025-09-30 {#version-4-0-3}"
+msgid "## 4.0.4: 2025-10-02 {#version-4-0-4}"
 msgstr ""
 
 msgid "### Improvements"

ja/news/index.md

@@ -5,7 +5,7 @@ upper_level: ../
 
 # おしらせ
 
-## 4.0.3: 2025-09-30 {#version-4-0-3}
+## 4.0.4: 2025-10-02 {#version-4-0-4}
 
 ### 改良
 

news/index.md

@@ -5,7 +5,7 @@ upper_level: ../
 
 # News
 
-## 4.0.3: 2025-09-30 {#version-4-0-3}
+## 4.0.4: 2025-10-02 {#version-4-0-4}
 
 ### Improvements