[gtk/appdata-build-date] Drop date attribute from our appdata files

[Matthias Clasen <matthiasc src gnome org>]

commit d6f4a0d2cfe3e3c605d09349a2fb1c8dda99e956
Author: Bernhard M. Wiedemann <bwiedemann suse de>
Date:   Mon Sep 6 10:05:31 2021 +0200

    Drop date attribute from our appdata files
    
    in order to make builds reproducible.
    See https://reproducible-builds.org/ for why this is good
    
    This was suggested by Matthias Clasen as an alternative to MR !3929

 demos/gtk-demo/org.gtk.Demo4.appdata.xml.in                |  2 +-
 demos/icon-browser/org.gtk.IconBrowser4.appdata.xml.in     |  2 +-
 demos/meson.build                                          | 10 ----------
 demos/widget-factory/org.gtk.WidgetFactory4.appdata.xml.in |  2 +-
 4 files changed, 3 insertions(+), 13 deletions(-)
---
diff --git a/demos/gtk-demo/org.gtk.Demo4.appdata.xml.in b/demos/gtk-demo/org.gtk.Demo4.appdata.xml.in
index a1a468c407..87f9267e67 100644
--- a/demos/gtk-demo/org.gtk.Demo4.appdata.xml.in
+++ b/demos/gtk-demo/org.gtk.Demo4.appdata.xml.in
@@ -33,7 +33,7 @@
   <developer_name>Matthias Clasen and others</developer_name>
   <content_rating type="oars-1.1"/>
   <releases>
-    <release version="@BUILD_VERSION@" date="@BUILD_DATE@">
+    <release version="@BUILD_VERSION@">
       <description>
         <p>A new build of GTK.</p>
       </description>
diff --git a/demos/icon-browser/org.gtk.IconBrowser4.appdata.xml.in 
b/demos/icon-browser/org.gtk.IconBrowser4.appdata.xml.in
index 8cfaaa2b49..87add81324 100644
--- a/demos/icon-browser/org.gtk.IconBrowser4.appdata.xml.in
+++ b/demos/icon-browser/org.gtk.IconBrowser4.appdata.xml.in
@@ -32,7 +32,7 @@
   <developer_name>Matthias Clasen and others</developer_name>
   <content_rating type="oars-1.1"/>
   <releases>
-    <release version="@BUILD_VERSION@" date="@BUILD_DATE@">
+    <release version="@BUILD_VERSION@">
       <description>
         <p>A new build of GTK.</p>
       </description>
diff --git a/demos/meson.build b/demos/meson.build
index de720925f6..550f90b0de 100644
--- a/demos/meson.build
+++ b/demos/meson.build
@@ -12,19 +12,9 @@ demo_conf_h = declare_dependency(
 )
 
 # appdata
-today = 'unknown'
-date = find_program('date',
-         required: false)
-if date.found()
-  r = run_command(date, '-I')
-  if r.returncode() == 0
-    today = r.stdout().strip()
-  endif
-endif
 
 appdata_config = configuration_data()
 appdata_config.set('BUILD_VERSION', meson.project_version())
-appdata_config.set('BUILD_DATE', today)
 
 subdir('constraint-editor')
 subdir('gtk-demo')
diff --git a/demos/widget-factory/org.gtk.WidgetFactory4.appdata.xml.in 
b/demos/widget-factory/org.gtk.WidgetFactory4.appdata.xml.in
index 7f8c4e5617..284b7419c2 100644
--- a/demos/widget-factory/org.gtk.WidgetFactory4.appdata.xml.in
+++ b/demos/widget-factory/org.gtk.WidgetFactory4.appdata.xml.in
@@ -34,7 +34,7 @@
   <developer_name>Matthias Clasen and others</developer_name>
   <content_rating type="oars-1.1"/>
   <releases>
-    <release version="@BUILD_VERSION@" date="@BUILD_DATE@">
+    <release version="@BUILD_VERSION@">
       <description>
         <p>A new build of GTK.</p>
       </description>